CHEMISTRY NECTA EXAMINATIONS
YEAR : 2018  SUBJECT : CHEMISTRY

THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATION COUNCIL

CHEMISTRY FTNA 2018

(i) Chemistry is a branch of Science which deals with:

  1. matter in relation to energy.
  2. matter in relation to decomposition.
  3. matter composition and its decomposition.
  4.  properties of conservation of matter.

(ii) Which of the following are the states of matter?

  1. Gas, liquid and mixture
  2. Gas, liquid and solid
  3. Element, compound and mixture
  4. Element, mixture and gas.

(iii)Which of the following are the main components of a fire triangle?

  1. Air, temperature and fire
  2. Oxygen, temperature and fuel
  3.  Oxygen, heat and fuel
  4. Oxygen, temperature and fire

(iv)The process of removing solid contaminants from water is known as:

  1. water decantation.
  2. water solidification.
  3. water purification.
  4. water sedimentation.

(v)How many zones are there in a non-luminous flame?

  1. Four zones
  2. Two zones
  3. Three zones
  4. Five zones

(vi)The process of coating iron or steel with zinc is known as:

  1. zinc painting.
  2. alloying.
  3. tin plating.
  4.  galvanization.

(vii)A certain element has atomic number W and mass number Y. The number of neutrons contained in its nucleus is:

  1. W
  2. W-Y
  3. Y-W
  4. Y+W

(viii)When a small amount of sugar is dissolved in a glass of water the mixture formed is:

  1. heterogeneous. 
  2. immiscible.
  3.  suspension. 
  4.  homogenous.

(ix)Fainting is a sudden loss of:

  1. confidence. 
  2. weight of the body. 
  3.  water in the body. 
  4.  consciousness.

(x)Why is fractional distillation of coal done?

  1.  To remove oxygen in the atmosphere.
  2. To remove volatile matter. 
  3.  To add oxygen in the furnace.
  4. To add volatile matter.

2. (a) Match each item in List A with a correct response in List B by writing its letter below the number of the corresponding item in the table provided.


LIST A  
LIST B

(i)It occurs between two ions with opposite charges.

(ii)It involves the sharing of electrons between atoms.

(iii)Shows the simplest ratio of atoms or ions in a compound.

(iv)Shows the actual number of each atom in a molecule.

(v)A force of attraction that holds atoms together to form molecules.

  1. Cation
  2. Anion
  3. Valency
  4. Electrovalent bond
  5. Covalent bond
  6. Empirical formula 
  7. Molecular formula 
  8. Chemical bond


(b) Fill in the blank spaces with the correct answer.

(i)A reaction that releases energy in the form of light and heat is called..........

(ii)A chemical process that occurs in steel and iron in the presence of air and water is known as..........

(iii)Oxygen, heat and fuel ar the three components that make..........

(iv)Injuries that result from the body coming into contact with heat of harmful chemicals are called..........

(v)A solution which can dissolve no more solute at a given temperature is called . 

SECTION B

3. (a) Indicate the corresponding meaning of the following warning signs.


Symbol

MEANING
i


ii


iii


iv


(b) Give four importance of First Aid.

4. Draw and give one function of the following apparatus:

Aparatus

Drawing
Function

(i) Measuring cylinder



(ii) Conical flask



(b)     By excluding a Bunsen burner, mention other three sources of heat that can be used in the laboratory.

 (c) Why is a Bunsen burner the best heat source in the laboratory? Give three (3) reasons.

5. Define the following terms:

(i)Brownian motion

(ii)Compound

(b) Identify whether the following is a physical or chemical change: 

(i) Cutting aluminium foil into pieces 

(ii) Lighting a match . 

(c) How can you separate the following mixtures? Briefly explain.

(i)Water and kerosene

(ii)Salt and water

(iii)Ethanol and water

6. During preparation of Hydrogen gas by the reaction between dilute Hydrochloric acid and Zinc granules, the granules slowly dissolve in acid to form solution X. 

(i) Name solution X .........

(ii) Write the chemical formula of X 

(b)How can hydrogen gas be tested?

(c)Mention four (4) chemical properties of hydrogen gas.

(d)List three (3) uses of Hydrogen gas.

7. (a) (i) How many electrons and protons are present in oxygen element

and aluminium element?

(ii) Write the electronic configuration of chlorine ion.

(b) Use the elements with chemical symbols: P, S and Cl to answer the following questions:

(i)Which elements is the most electronegative?

(ii)Mention the least electronegative element.

(iii)Which element has the largest atomic structure?

(c) Study the following table with elements lettered F, G, L, M and J, then answer the question that follows

Element
Atomic Mass
Atomic Number
F
16
8
G
19
9
L
23
11
M
12
6
J
20
10

(i)How many neutrons are present in element L?

(ii)Which group and period of the periodic table does element F belong?

(iii)Which element does not readily form compounds? Give a reason.

8. Write four (4) sources of energy used for cooking in most Tanzanian societies.

(b) List four (4) characteristics of a good fuel.

 (c) List two areas where scientific procedure can be applied.

9. Outline six common apparatus used in the laboratory preparation of oxygen gas using hydrogen peroxide.

(b) Outline four uses of oxygen in everyday life situation.

10. (a) Define the following terms:

(i)Valency

(ii)Oxidation state

(iii) Anion

(iv)Cation

(b) Calculate the oxidation state of the underlined elements in the following radicals:

(i) NH4+

(ii) SO42

(iii) ClO3

(c) A compound consists of 40% carbon, 6.67% hydrogen and 53.33% oxygen. If its relative molecular mass is 60, calculate the following:

(i)Empirical formula

(ii)Molecular formula

YEAR : 2017  SUBJECT : CHEMISTRY

(i)  Which statement gives a clear meaning of Chemistry?

  1. The study of matter in relation of energy
  2. The study of nature and properties of matter
  3. The study of matter and arrangement of particles
  4. The study of matter and chemical reaction

(ii)  The mass number of an atom is determined by:

  1. protons and neutrons 
  2.  protons and electrons 
  3.  neutrons and electrons 
  4. protons alone

(iii)Which of the following is a metal?

  1. Water 
  2. Chlorine
  3. Sodium
  4.  Nitrogen

(iv)Air entering the Bunsen burner barrel can be controlled by

  1. metal ring 
  2.  air hole
  3. metal jet
  4. air ring

(v)  How many atoms are there in a water molecule

  1. Two 
  2. . Three 
  3.  Four 
  4. Five

(vi)Which neutral atom has the same number of eletrons as Mg2+?

  1. Magnesium 
  2.  Sodium
  3.  Neon
  4.  Argon

(vii)  The appropriate extinguisher used to put off fire caused by cooking oil is:

(vii)  The appropriate extinguisher used to put off fire caused by cooking oil is:

  1. Water extinguisher
  2. Carbon extinguisher
  3. Wet chemical extinguisher
  4. Dry air extinguisher

(viii)  A non-luminous flame is obtained if the hole is:

  1. fully opened
  2. partially opened
  3. closed
  4. half opened

(ix)Which is the least abundant gas in the air?

  1. Nitrogen
  2. Oxygen
  3. Neon
  4. Carbon dioxide

(x)  The process which produces energy in form of heat and light is called:

  1. decomposition
  2. combustion
  3. distillation
  4. sublimation

SECTION B

2.                        (a) Match each items in List A with a correct response in List B by writing

       its letter below the number of the corresponding item in the table provided:

 

LIST A

LIST B

I) A process of separating a mixture of sodium chloride and ammonium chloride.

II) A method used to separate oil and water.

III)A method by which coloured substances are separated and identified.

IV)A method by which salt and water can be separated.

V) A method used to get the solvent from the solution mixture.

 

 

A.Evaporation

B. Filtration

C. Boiling

D.Chromatography

E. Distillation

F.Layer separation

G.Decantation

H.Sublimation


(b)       Fill in the blanks with the correct answer

(i)      A flame is a zone of burning gas that produces ..................

(ii)    The arrangement of electrons in different shells in the atom is

called ..................

(iii)A type of gas fuel derived from decomposing biological waste is called ..................

(iv)  The three components of the fire triangle are heat fuel and

(v)    A substance that speeds up a chemical reaction but remains chemically unchanged is called ..................

3.   (a) Draw and state one function of each of the following apparatuses: (i) Burette

(ii)      Filter funnel

(iii)    Beaker

(b)       Define the following terms:

(i) First aid

(ii) Laboratory

(c)        List two components of a first aid kit.

4.   Define matter.

(b)       Tell whether the following is a chemical change or physical change.

(i)      Rotting of mango.

(ii)    Clouds changing into rain. (iii) Decaying of teeth.

(c)        State four differences between a chemical change and physical change

5.   Write the names and formulae of the two chemicals that can be used in the preparation of oxygen gas.

(b)       (i) State an appropriate method of collecting oxygen gas based on solubility and density of the gas in water. (ii) How can oxygen gas be tested?

(c)        List four uses of oxygen gas.

6.   (a) Write the names of the following radicals:

(i)

(ii)    C103

(iii)  poi-

(b)       Calculate the oxidation state of the underlined element in the following compounds:

(i)      NH4Cl

(ii)    A1203

(iii)Na2S04

(iv)  H202

(c)        Calculate the percentage composition by mass of the underlined element in the following compounds:

7.     (a) (i) Why may a flame produced by a "spirit lamp" not be good for  heating in the laboratory? Give two reasons.

(ii) Name the type of flame produced by a spirit lamp.

(b)       By using locally available materials in your school, state how the fire can be extinguished in the following situations:

(i)      Kerosene spilled on the floor catches fire.

(ii)    Friends clothes catch fire which gets out of her control.

(c)        Suggest the suitable method of preventing rust in the following:

(i)      Moving parts of machines e.g. motorcycle chain. (ii) Motor vehicle (car) bodies.


8.     The following is a part of periodic table with some elements represented by letters. Study it and answer the questions that follow.

Vlll

 A



 


 B

C

 

 

 

 

 

 

 D

E

 

 

 

 

 F

 G

 

 

 H

 

 

 

 

 

 


(a) (i) Mention the names of the elements represented by the following letters A to H

(ii) Write the electronic configuration of the elements represented by letters G and H.

(b)    (i)Identify the letters which represent the elements with the following properties: (i) Zero valency

(ii)   Lightest atom ..... ........

(iii)Alkaline earth metal .............

9.                        Hydrogen gas is prepared in the laboratory by reacting dilute hydrochloric acid and zinc granules.

(a)Write an alternative acid that can be used to prepare hydrogen instead of dilute hydrochloric/acid.

(b)       Given two physical and two chemical properties of hydrogen.

(c)What will happen if a burning wooden splint is lowered in a test tube containing hydrogen gas?

(d) Give two uses of hydrogen gas in daily life.


10.       The following figure shows the apparatus that can be used to separate three liquids: cooking oil, kerosene and water with density 0.92g/cm3 and 1.00g/cm3 respectively.

(i) Name the apparatus shown by the given figure (ii) By giving a reason, identify liquids A and C

Liquid A .............

Liquid C

Reason .............

(b)       The following table shows the name and the chemical formula of the product formed when ions combine together. Complete filling the table Table showing combination of ions

ions

Name

Formula

 Ca2+

 

Calcium chloride

 

 Al3+

so42-

 

 Al(SO4)3

 H+

 

Hydrogen sulphate

 

 

YEAR : 2016  SUBJECT : CHEMISTRY

(i) Chemistry is defined as:

  1. The scientific study of matter, compounds and chemical reactions
  2. The scientific study of compounds, mixtures and organic substances
  3. The scientific study of composition, structure and properties of matter
  4. The study of relation between human being, medicine and pollution.

(ii) A non-luminous flame is the most applicable flame for heating purposes because:

  1. It is very noisy
  2. It has no soot
  3. It is very hot
  4. It has no colour

(iii) Matter is defined as anything that has:

  1. Volume and occupies space
  2. Mass and occupies space
  3. Mass and occupies density 
  4. Density and space

(iv) Which of the following process is used in preventing rust of an iron?

  1. Water
  2. Boiling
  3. Salting
  4. Galvanization

(v) Water is a universal solvent because:

  1. It is available everywhere
  2. It boils at 1000C
  3. It dissolves most of the solutes
  4. It dissolves all crystals in compounds

(vi)  Carbon has two main isotopes, 12 C and 14 C with relative abundance of 98.89% and 1.11% respectively. Calculate the relative atomic mass of carbon.

  1. 13.5
  2. 12.01
  3. 6
  4. 27

(vii) Class F fire can best be extinguished by using

  1. Carbon dioxide
  2. Wet chemical
  3. Water
  4.  Sand

(viii)Which of the following components can be separated by filtration method?

  1. Sand and water 
  2. Kerosene and water
  3. Ethanol and water 
  4. NaCl and water

(ix) Which of the following is the colour change when cobalt chloride paper is used to test the presence of water?

  1. White when dry and pink when wet
  2. Blue when dry and pink when wet
  3. Yellow when dry and pink when wet
  4. Pink when dry and blue when wet

(x) All domestic utensils made of iron undergo rusting when exposed to

  1. Air and fire
  2. Air and oil
  3. Air and water
  4. Water and oil

SECTION B

2. Match each item in List A with a correct response in List B by writing its letter bellow the number of the corresponding item in the table provided

 

 

LIST B

(i)       Atoms of the same element that contain different numbers of neutrons

(ii)     Elements with both metallic and non-metallic characteristics.

(iii)  Sub atomic particle not found in the nucleus of the atom.

(iv)   The number of protons found in the nucleus of the atom.

(v)     The total number of protons and neutrons in the nucleus of the atom.

(vi)   The number of unpaired electrons on an atom.

(vii)       Elements which are very stable and rarely react.

(viii)    Elements which form diatomic molecules.

(ix)   Sub atomic particle with no charge.

(x)     A group of atoms with unpaired electrons

A.

B.

C.

D.

E.

F.

G.

H.

I.

K.

L.

M.

N.

O.

Atomic number

Electron

Radical

Metalloids Isotopes

Mass number

Neutron

Allotropes

Noble gases

Period

Group

Proton

Valence Atomic radii

Halogens



SECTION C

3.   Write the name and chemical formula of two important chemical substances used in the laboratory preparation of oxygen gas. (b) Mention four physical properties of oxygen gas.

4.   Write four sources of energy used for cooking in Tanzania (b) What are the four characteristics of a good fuel?

5.    What are the five steps used in lighting a Bunsen burner?

(b)     Classify fuels based on their physical state and for each class give two examples.

6. Explain three factors which affect the problem being investigated (b) Explain two areas where scientific procedure is applied.

7. (a) Differentiate metals from non metals

(b) Classify each of the following elements into their respective groups and periods.

(i)        Berylium 

(ii)      Magnesium .. .................................

(iii)    Neon

(iv)     Potassium „............. ................... ....

(v)      Chlorine

8. Explain each of the following terms:

(i)        Burn

(ii)       Bruises

(iii)    Fainting ..............................................

(b)     What are the six procedures which can be used to help a person with severe bleeding on the wound?

9.  The following figure shows a set-up used to prepare gas

Water


(a)   Identify gas Q

(b)    Identify other two chemical substances that could be used in the laboratory to prepare gas Q if zinc is not present. (c) State two physical properties of gas Q.

(d) State two chemical properties of gas Q.

10. (a) The diagram below shows the bonding between two elements A and B.


(i)      Write the valence of B.

(ii)    Identify the valence of A.

(iii)  State the type of bonding formed between A and B.

(iv)  Write the formula of the compound formed by A and B.

 (b) Write the formula of the compound formed by the combination of:

(i) NH4+ and SO 2-

(ii) Na+ and C032-

(c)      State the number of atoms of each element in CaClz.

(d)      Calculate the oxidation state of sulphur in SO 2-.

YEAR : 2015  SUBJECT : CHEMISTRY

(i) Which of the following is the most correct statement about hypothesis?

  1. A fundamental concept or theory
  2. A possible explanation to the problem.
  3. An important statement of a research conclusion 
  4. A stage in data interpretation.

(ii) Which of the following is not among the gases composing air?

  1. Noble gases
  2. Carbon dioxide
  3. Nitrogen
  4. Hydrogen

(iii) When an atom loses or gains electron, it becomes:

  1. An ion 
  2. An anion
  3. A cation 
  4. A charged ion

(iv) A change from gaseous state to solid state without passing through a liquid state is called:

  1. Deposition 
  2. Sublimation
  3. Condensation 
  4. Solidification

(v) What is the type of a fire associated with electrical equipment?

  1. Class E 
  2. Class C
  3. Class F 
  4. Class B

(vi) Which among the following are the two processes involved during distillation?

  1. Evaporation and sublimation 
  2. Evaporation and crystallization
  3. Evaporation and condensation 
  4. Evaporation and decantation

(vii) Which of the following set of nuclide notation represents isotopes? 

  1. 18 X 16 X 19
  2. 18 X 18 X X 
  3.  16 x 18 x 1890x 
  4.  16 X 1789x,

(viii) The chemical used to test the presence of water in a substance is:

  1. Cobalt Il oxide
  2. Cobalt Ill oxide
  3. Cobalt -chloride 
  4. Copper Il chloride

(ix) When a burning fuel produces blue colour it means there is:

  1. Adequate supply of oxygen with production of soot
  2. Inadequate supply of oxygen with production of more heat.
  3. Inadequate supply of oxygen with production of soot.
  4. Adequate supply of oxygen with production of more heat.

(x) Which of the following is the best apparatus for measuring accurately a fixed volume of a given solution?

  1. Measuring cylinder
  2. Beaker
  3. Pipette 
  4.  Burette

2. Match each item in List A with a correct response in List B by writing its letter below the number of the corresponding item in the table provided.


Group of elements which react quickly with water to form alkaline solution.

The ability of an atom to attract an electron.

(iii)    Group of elements in which their shells are completely filled up.

(iv)     A vertical column of elements in the periodic table.

(v)      Group element which react slowly with water to form alkaline solution.

Group of elements which react with metals to form salts.

(vii) Group of elements which react by receiving electrons.

(viii)The systematic arrangement of elements according to their increase in atomic numbers.

(ix)     Group of elements with high densities and melting points, and often act as catalysts.

(x)      Group of elements which have both metallic and non-metallic characteristics.

A.    Metalloids

B.     Non-metals

C.     Periodicity

D.    T r a n s i t i o n elements

E.    Electronegativity

F.     Alkali metals

G.    Halogens

H.    Periodic law

I.       Alkali earth metals

J.      Rare non metals

K.    Period

L.     Noble gases

M.   Periodic table

N.    Group



   
















SECTION C

3.     (a) Define the following terms:

(i)       Oxidation state

(ii)     An element .......„

(iii)   A compound

(iv)    Fainting

(b)      Write the chemical formula for each of the following compounds:

(i)         Sodium sulphate

(ii)       Sodium chloride ..

(iii)      Calcium nitrate ......... 

(iv) Calcium oxide .

4.      Gas X can be prepared in the laboratory by the decomposition of hydrogen peroxide.

(a)        Identify gas X ..

(b)        State three physical properties of Gas

Mention three chemical properties of gas X. (d) State three uses of gas X.

5.         Write the name of each of the following compounds:

(i)       (NH4)2C03

(ii)     caC12

(iii)

(iv) KC103

(b)      Give three differences between the following:

(i)           Electrovalent compounds and covalent compounds. (ii) Solutions and suspensions.

6.        State two chemical properties of water.

Calculate the molar mass of each of the following compounds:

          (ii) NaHC03                        (iii) Fe203

(c) State whether each of the following is a chemical or physical change:

          (i) Burning of charcoal .........

             (i)         Rusting of iron sheets

7.      (a) Study the following Periodic Table and then answer the questions that follow.

                      I                                                                                   VIII

A

II          iii IV       V         VI     VII

 B

 

C

 

 D

 

 E

 

 

 F

 G

 

 

 

 

H

 

 

 

 

(i)        Write the collective name of elements in:

                                Group Il ..                             Group VIII 

(ii)       Name the elements which are represented by the following letters:

(iii)     Write the electronic configuration of the following elements:

(b)      Name two products in each of the following fields made by the application of chemistry.

(a)      Medicine

(b)     Food and be average industry

8.     (a) Calculate the oxidation number of the underlined elements:

         (i)   K2C2O4         (II) SO32-

(b)      What is the use of each of the following apparatus? (i) Thistle funnel    (ii) Pipette .........

                (iii) Wire gauze .........          (iv) Burette .........

9.    When dilute hydrochloric acid is reacted with zinc metal, gas Z is formed.

(a)     Identify the name of gas Z.

(b)     Mention four physical properties of gas Z. State two uses of gas Z.

10.   Define the following terms:

(i)        Empirical formula .........

(ii)       Molecular formula .........

(b)      A compound consists of 85.7% carbon and 14.3% hydrogen by mass. If its relative molecular mass is 56, calculate:

(i)         Empirical formula.

(ii)       Molecular formula.

YEAR : 2015  SUBJECT : CHEMISTRY

(i) Which of the following is the most correct statement about hypothesis?

  1. A fundamental concept or theory
  2. A possible explanation to the problem.
  3. An important statement of a research conclusion 
  4. A stage in data interpretation.

(ii) Which of the following is not among the gases composing air?

  1. Noble gases
  2. Carbon dioxide
  3. Nitrogen
  4. Hydrogen

(iii) When an atom loses or gains electron, it becomes:

  1. An ion 
  2. An anion
  3. A cation 
  4. A charged ion

(iv) A change from gaseous state to solid state without passing through a liquid state is called:

  1. Deposition 
  2. Sublimation
  3. Condensation 
  4. Solidification

(v) What is the type of a fire associated with electrical equipment?

  1. Class E 
  2. Class C
  3. Class F 
  4. Class B

(vi) Which among the following are the two processes involved during distillation?

  1. Evaporation and sublimation 
  2. Evaporation and crystallization
  3. Evaporation and condensation 
  4. Evaporation and decantation

(vii) Which of the following set of nuclide notation represents isotopes? 

  1. 18 X 16 X 19
  2. 18 X 18 X X 
  3.  16 x 18 x 1890x 
  4.  16 X 1789x,

(viii) The chemical used to test the presence of water in a substance is:

  1. Cobalt Il oxide
  2. Cobalt Ill oxide
  3. Cobalt -chloride 
  4. Copper Il chloride

(ix) When a burning fuel produces blue colour it means there is:

  1. Adequate supply of oxygen with production of soot
  2. Inadequate supply of oxygen with production of more heat.
  3. Inadequate supply of oxygen with production of soot.
  4. Adequate supply of oxygen with production of more heat.

(x) Which of the following is the best apparatus for measuring accurately a fixed volume of a given solution?

  1. Measuring cylinder
  2. Beaker
  3. Pipette 
  4.  Burette

2. Match each item in List A with a correct response in List B by writing its letter below the number of the corresponding item in the table provided.


Group of elements which react quickly with water to form alkaline solution.

The ability of an atom to attract an electron.

(iii)    Group of elements in which their shells are completely filled up.

(iv)     A vertical column of elements in the periodic table.

(v)      Group element which react slowly with water to form alkaline solution.

Group of elements which react with metals to form salts.

(vii) Group of elements which react by receiving electrons.

(viii)The systematic arrangement of elements according to their increase in atomic numbers.

(ix)     Group of elements with high densities and melting points, and often act as catalysts.

(x)      Group of elements which have both metallic and non-metallic characteristics.

A.    Metalloids

B.     Non-metals

C.     Periodicity

D.    T r a n s i t i o n elements

E.    Electronegativity

F.     Alkali metals

G.    Halogens

H.    Periodic law

I.       Alkali earth metals

J.      Rare non metals

K.    Period

L.     Noble gases

M.   Periodic table

N.    Group



   
















SECTION C

3.     (a) Define the following terms:

(i)       Oxidation state

(ii)     An element .......„

(iii)   A compound

(iv)    Fainting

(b)      Write the chemical formula for each of the following compounds:

(i)         Sodium sulphate

(ii)       Sodium chloride ..

(iii)      Calcium nitrate ......... 

(iv) Calcium oxide .

4.      Gas X can be prepared in the laboratory by the decomposition of hydrogen peroxide.

(a)        Identify gas X ..

(b)        State three physical properties of Gas

Mention three chemical properties of gas X. (d) State three uses of gas X.

5.         Write the name of each of the following compounds:

(i)       (NH4)2C03

(ii)     caC12

(iii)

(iv) KC103

(b)      Give three differences between the following:

(i)           Electrovalent compounds and covalent compounds. (ii) Solutions and suspensions.

6.        State two chemical properties of water.

Calculate the molar mass of each of the following compounds:

          (ii) NaHC03                        (iii) Fe203

(c) State whether each of the following is a chemical or physical change:

          (i) Burning of charcoal .........

             (i)         Rusting of iron sheets

7.      (a) Study the following Periodic Table and then answer the questions that follow.

                      I                                                                                   VIII

A

II          iii IV       V         VI     VII

 B

 

C

 

 D

 

 E

 

 

 F

 G

 

 

 

 

H

 

 

 

 

(i)        Write the collective name of elements in:

                                Group Il ..                             Group VIII 

(ii)       Name the elements which are represented by the following letters:

(iii)     Write the electronic configuration of the following elements:

(b)      Name two products in each of the following fields made by the application of chemistry.

(a)      Medicine

(b)     Food and be average industry

8.     (a) Calculate the oxidation number of the underlined elements:

         (i)   K2C2O4         (II) SO32-

(b)      What is the use of each of the following apparatus? (i) Thistle funnel    (ii) Pipette .........

                (iii) Wire gauze .........          (iv) Burette .........

9.    When dilute hydrochloric acid is reacted with zinc metal, gas Z is formed.

(a)     Identify the name of gas Z.

(b)     Mention four physical properties of gas Z. State two uses of gas Z.

10.   Define the following terms:

(i)        Empirical formula .........

(ii)       Molecular formula .........

(b)      A compound consists of 85.7% carbon and 14.3% hydrogen by mass. If its relative molecular mass is 56, calculate:

(i)         Empirical formula.

(ii)       Molecular formula.

YEAR : 2014  SUBJECT : CHEMISTRY

(i) An isotope of carbon has an atomic number 6 and a mass number of 14, this means that it has:

  1. 6 protons, 8 neutrons, 6 electrons
  2. 8 protons, 6 neutrons, 8 neutrons
  3. 6 protons, 14 neutrons, 6 electrons
  4. 14 protons, 6 neutrons, 14 electrons.

(ii) Which of the following gives the correct meaning of air?

  1. Mixture of Nitrogen, Oxygen and dust particles.
  2. Mixture of Nitrogen, Oxygen and Carbon dioxide. 
  3. C. Mixture of Nitrogen, Oxygen and Water vapour 
  4. Homogenous mixture of gases.

(iii) Why is water a universal solvent?

  1. It is neither acidic nor basic than any other known liquid.
  2. It dissolves more substances than any other known liquid.
  3. It occurs naturally in all the three states of matter than any other liquid.
  4. It dissolves both organic and inorganic solutes than any other liquid.

(iv) How many numbers of shells are there in Magnesium atom?

  1.  
  2.  2
  3.  3
  4.  4

(v) Technicians prefer to use blue flame in welding because:

  1. It is bright and non-sooty
  2. It is light and non-sooty
  3. It is very hot and large
  4. It is very hot and non-sooty

(vi)  Which of the following is the characteristic of solid?

  1. It is packed together but does not have definite size. 
  2. It is compact packed and has definite shape and size. 
  3. It is loosely packed with irregular order. 
  4. It is closely packed with uniform shape.

(vii) What is the oxidation state of Chlorine in KCIO3?

  1. +2
  2. -5
  3. +5
  4. +3

(viii) Which of the following is a sequential method of separating mixture of salt and sand?

  1. Evaporation, filtration and decantation
  2. Decantation, evaporation and filtration
  3. Sedimentation, evaporation and filtration 
  4. Decantation, filtration and evaporation

(ix) Which of the following is the best apparatus for measuring accurately the volume of a given solution?

  1. Measuring cylinder
  2. Burette
  3. Beaker
  4. Conical flask

(x) The factors that affect the problem being investigated are referred to as:

  1. Dependent factors
  2. Variables
  3. Independent factors
  4. Conditions

2.   Match each item in List A with a correct response in List B by writing its letter below the number of the corresponding item in the table provided.

LIST A

LIST B

(i)       Method of recovery of both solute and solvent from a liquid.

(ii)     Method of separating two miscible liquids which their boiling points are close together.

(iii)   Method of separating two immiscible liquids.

(iv)   Method of separating two solids by heating in a way that one changes its state directly to gas.

(v)     Method of separating coloured components using a moving solvent on materials that absorb such solvent.

(vi)   A suitable method of separating edible oils from seeds.

(vii) Method of separating solid mixture which contains iron.

(viii)Method of separating an insoluble solid from a liquid.

(ix)    Method of separating a soluble solid and a solvent.

(x)      Method of separating liquids which forms a suspension with a solvent

A.     Layer separation

B.      Chromatography

C.      Simple distillation

D.     Condensation

E.      Hand picking

F.      Fractional distillation

G.     Sieving

H.     Solvent extraction

I.        Evaporation

J.       Sublimation

K.     Magnetisation

L.      Magnetism

M.    Deposition

N.     Decantation

O.     Filtration

3.    (a) Define the following terms:

(i)       Emulsions

(ii)     A solution

(iii)   Atom

(iv)    Radical

(b)      Write the chemical formula for each of the following compounds:

(i)        Sodium sulphide

(ii)      Beryllium chloride

(iii)    Copper (I) oxide

(iv)     Potassium oxide

4.    Draw a diagram to show laboratory preparation of oxygen using hydrogen peroxide. In the diagram, label all the compounds and elements involved in the preparation.

 Briefly explain how you would distinguish ordinary air from pure oxygen.

(c) List two chemical properties of oxygen gas.

5.   Write the name of each of the following compounds:

(i) Cuo (ii) PC13 (iii) N204

(b)      Give three differences between the following:

(i)        Physical changes and chemical changes

(ii)      Mixture and compounds

6.    Give four physical properties of water

 Calculate the molar mass of each of the following compounds: (i) Na3P04

(iii) caC03

7.      (a) Study the following periodic table and then answer the questions that follow:

                    1                                                                       V111

 

11                              111     IV

V

VI

Vll

 

 

s

 

 T

 

U

 V

 

w

 

 

 

x

 

 

 Y

z

 

 

 

 

 

(i) Name and write the chemical symbols for the elements represented by the following letters: S,Z,W,X

(ii) Write the electronic configuration for the elements represented by the following letter.T, U, V, Y

(b) Name two products in each of the following fields made by the application of chemistry.

Field

                     Products

(i) Home care and cosmetics

(ii) Transport

8.         (a) Calculate the oxidation number of the underlined elements:

(i) HSO-3;  (ii) N02-

(b)      What is the use of each of the following apparatuses?

(i)        Tongs .             (ii) Spatula.........

                (iii) Pipette.........     (iv) Crucible .........

9.         (a) Study the experiment diagram below and answer the questions that follow.

(i)       What happens to the copper (II) oxide during the experiment?

(ii)      What happens to the two pieces of cobalt paper? (iii) Write a word equation for the reaction.

(b)      Mention four chemical properties of hydrogen gas.

10.     (a) Define the following terms:

(i)      Covalent bond

(ii)    Electrovalent bond

(b)      A compound consists of 82.8% carbon and 17.2% hydrogen by mass The vapour density of the compound is 29. Calculate:

(i)        Empirical formula.

(ii)      Molecular formula.

YEAR : 2013  SUBJECT : CHEMISTRY

 (i) The apparatus used for grinding granular chemicals in the laboratory include:

  1. Crucible and watch glass
  2. Mortar and pestle
  3. Pestle and pair of tongs 
  4. Spatula and basin

 (ii)  The substances that can be used to extinguish fire are:

  1. Carbon dioxide and sand
  2. Carbon dioxide and sugar
  3. Nitrogen and sand
  4. Nitrogen and water

 (iii) Which of the following electronic configurations are of metals?

A. 2:8:1 and 2:5

B. 2:8:2 and 2:6

C. 2:8:3 and 2:8:8:7

D. 2:8:6 and 2:8:8:7

 (iv) When sugar is dissolved in water, a uniform mixture is formed. The resulting mixture is called a:

  1. Solute
  2. Solution
  3. Solvent
  4. Suspension

 (v) Flammable chemicals are those which:

  1. Burn skin
  2. Catch fire easily
  3. Explode
  4. Extinguish fire

 (vi) Which of the following can be classified as a renewable source of energy?

  1. Biomass
  2. Coal
  3. Coke
  4. Petroleum

 (vii) The part of Bunsen burner that controls the amount of air coming in is called:

  1. Air hole
  2.  Barrel
  3.  Collar 
  4.  Jet

 (vii) The part of Bunsen burner that controls the amount of air coming in is called:

  1. Air hole
  2.  Barrel
  3.  Collar 
  4.  Jet

 (ix) The simplest formula of a compound formed when combining 13g of aluminum and 17g of chlorine is:

  1. AlCl
  2. Al2Cl
  3. Al3Cl2
  4. AlCl3

 (x) The second step in the scientific procedure is:

  1. Data collection and analysis
  2. Data interpretation
  3. Experimentation and observation
  4. Hypothesis formation

SECTION B

2.  Match each item in List A with a correct response in List B by writing its letter below the number of the corresponding item in the table provided.

 

LIST A

LIST B

(i)        Ability of an atom to gain or attract electrons towards itself

(ii)       Addition of oxygen to or removal of hydrogen from a substance

(iii)     A substance which behaves in three states of matter

(iv)     Bond formed between two atoms due to sharing of two electrons from each other.

(v)       Combining power of an element

(vi)     Liquids which form layers when mixed

(vii)   Reddish brown coating on metals

(viii)Supports burning of substances

Ox) The number of electrons in the outermost shell

(x) Treatment and purification of water for human uses.

A.     Chlorination

B.     Covalent

C.     Electronegativity

D.     Electropositivity

E.     Evaporation

F.     Groups

G.     Ionic

H.     Kerosene and water

I.       Oxidation

J.      Oxygen

K.     Reduction

L.     Rust

M.    Sugar and alcohol

N.     Valency

O.     Water



SECTION C

3.      (a) What do you understand by the following terms?

(i)        Empirical formula .

(ii)       Relative atomic mass .........

(b)      A certain compound K contains 15.8% carbon and 84.2% sulphur. The molar mass of K is 76g/mol. Determine its:

(i)       simplest formula ... ......

(ii)     molecular formula .........

4.        (a) Define the following terms as applied in Chemistry:

(i)        Flame

(ii)      Bunsen burner

(iii)    Laboratory

(b)      List four properties of each of the following:

(i)       A luminous flame

(ii)     A non-luminous flame

(c) Write the chemical formula for each of the following compounds:

(i)       Sodium carbonate

(ii)     Calcium nitrate

(iii)   Ammonium chloride

5.        (a) Calculate the percentage by composition of the underlined elements in the following compounds: (i) Na2S04

  (ii) Ca(HCO3)2

(b)      Give the use of each of the following components which are found in the First Aid kit:

(i)       Plaster .........

(ii)     A pair of scissors (iii) Cotton wool ......... (iv) Gloves .........

(c) Categorize the following changes as either chemical or physical:

(i)         Freezing of juice in a bottle .........

(ii)        Rusting of iron .........

(iii)      Burning of wood .

(iv)      Drying of wet clothes .........

6.         (a) Define the following terms:

(i)       Chemistry

(ii)     Element

(iii)   Catalyst

(b)      Give three differences between the following:

(i)       Compound and mixture

(ii)     Suspension and solution

7.     (a) The figure below shows the relationship among three states of matter. Name the processes involved in A, B, C and D.


(b)      State the valency of each of the following atoms:

(i)       Aluminium             (ii) Neon

               (iii) Sulphur                   (iv) Potassium

(c)       Give the chemical formula for the combination of the following sets of ions:

(i)       Mg2+, PO3-4

(ii) Fe3+, SO42-

8.    (a) Write a word equation for each of the following reactions:

(i)      Calcium burns in Oxygen .........

(ii)    Sodium reacts with water ... ... ...

(b)      What do you understand by the following terms?

(i)       Water treatment

(ii)     Water purification

(c)       Mention six uses of water in economic activities.

9.        Gas "L" has the following properties: it is highly flammable, readily combines with other elements, readily reacts with other chemical substances and is a strong reducing agent.

Name the gas L

(b)      What is the method used to collect gas in the laboratory? Give a reason.

Give four uses of gas L

10.                   Mention four chemical properties of Oxygen.

(b)      Find the oxidation number of each of the underlined elements in the following: (i) KC103

(ii)

(c) Use the IUPAC system to name each of the following chemical compounds:

               (i) CuO                                       (ii) CaSO4

              (iii) HN03                               (iv) ZnC12

YEAR : 2012  SUBJECT : CHEMISTRY

(i) All domestic utensils made of iron undergo rusting when exposed to:

  1.  Air and fire
  2.  Air and oil
  3. Air and water 
  4. Water and oil

(ii) When a small amount of common salt is dissolved in a glass of water the mixture formed is:

  1. Heterogeneous 
  2. Homogeneous 
  3. Immiscible 
  4. Suspension

(iii) A chemist should acquire all of the following skills except:

  1. Experimentatio
  2. Observation 
  3. Problem identification 
  4. Surgery

(vi) An important property of oxygen which distinguishes it from other gases is that it:

  1. Burns and supports combustion
  2. Burns but does not support combustion 
  3. Neither burns nor supports combustion
  4. Supports combustion but does not burn

(v) The process of chlorination in water treatment aims at:

  1. Forming suspension 
  2. Killing micro-organisms 
  3. Making syrup 
  4. Removing bad odour

(vi) One of the following is not correct about coke being a better fuel than coal as it:

  1. Does not produce carbon dioxide gas
  2. Does not produce poisonous gas
  3. Has a higher heat content 
  4. Is clean and smokeless

(vii) Class E fire can best be extinguished by using:

  1. Carbon dioxide 
  2. Fire blanket
  3. Sand 
  4. Water

(viii) The following is a set of apparatuses which are used for heating:

  1. Crucible, test tube, evaporating dish
  2. Evaporating dish, tongs, crucible
  3. Test tube, evaporating dish, tongs
  4. Tongs, crucible, test tube

(ix) Which of the following methods can be used to get oil from cotton seeds?

  1. Decantation 
  2. Distillation
  3. Grinding and distillation 
  4. Grinding followed by squeezing

(x) Which of the following apparatuses is suitable for measuring volumes of smaller quantities of liquids?

  1. Beaker 
  2. Burette
  3. Conical flask 
  4. Measuring cylinder

2.    Match each item in List A with a response in List B by writing its letter below the number of the corresponding item in the table provided.

LIST A

LIST B

(i)         A method used to separate mixtures of two or more liquids that form homogeneous solution by means of fractional column.

(ii)       A substance that absorbs moisture from the atmosphere and dissolves in it.

(iii)     Elements with stable structure.

(iv)      Molecular mass of calcium carbonate.

(v)       Poisonous gases prepared in it.

(vi)      Produces a "pop" sound.

(vii)    Quiet and unsteady flame.

(viii)  Smokeless solid fuel.

(ix)      Source of energy derived from animal waste,

(x)       Used to prevent direct heat to reach the apparatus.

A.        Biogas

B.        Chromatograph

C.        Coke

D.        Corrosive

E.        Deliquescent

F.        Fractional distillation

G.        Fume chamber

H.        Hydrogen

I.          Luminous flame

J.         Noble gases

K.        Non-luminous flame

L.        Oxygen

M.       Wire gauze

 N. 80g/mol 

O. 100g/mol.















SECTION C

3.  (a) Mariam was preparing food for her family using hot oil in a frying pan. Accidentally the pan tripped over and a huge fire spread over her kitchen floor.

(i)        Mention two extinguishers which would be appropriate for putting out the fire.

(ii)      Which fire extinguisher would be dangerous to use when trying to put out the fire in (a) above? Give reason. (b) Mention three conditions for a fire to start.

(c) (i) What is combustion?

(ii) Give three areas where combustion is applied.

4.   (a) In an experiment, two iron nails A and B were used whereby painting was applied on nail A. The two nails were placed in a moist environment and after one month the weight of each nail was determined. Which of the two nails would be heavier? Give reason.

(b)   State the method which will be used to protect each of the following from rusting:

   (i)   Covering iron sheets with a layer of most reactive metals (ii) Bicycle chain

(c)  Find the oxidation number of the underlined elements in the following:

  (i)  Mn04

(i) K2Cr07

5.         Use the details given below about elements P, Q, R, S and T to answer questions (a) and (b).

(a) (i) Write down the electronic configuration of the elements represented by letters from P to T:

(i)       How many neutrons are present in element Q? . 

(c)     Name the type of   bonds that will be formed in the combination between the following elements: 

       (i) Q and T

(ii) S and T

(d)     Write the chemical symbol for each of the following elements:

(i)       Silver

(ii)     Lead .........

(iii)  Manganese .........

6.         (a) Explain why petroleum and coal are non-renewable resources of energy. (b) What is fuel?

(c) The problem facing Tanzania society is misuse of charcoal and firewood as a source of fuel. Give two points of advice to the society on how to use less charcoal and firewood efficiently.

(d) Mention three categories of fuel and give two examples in each category.

7.    (a) List down four careers that are a result of studying Chemistry.

(b) The following are possible causes of accidents which can occur in the Chemistry laboratory. State how you can avoid them.

(i)         Poisonous chemicals left in an unlocked cupboard .........

(ii)       A student picking up a bottle containing concentrated H2S04 acid by the neck .........

(iii)      Concentrated acids stored in the upper most shelf of cupboard

8.     An experiment showed that 13.88g of calcium chloride were obtained from the combination of 5g of calcium with unknown relative mass of chlorine.

(i)         What is the simplest formula of calcium chloride .

(ii)       What kind of bond exists between calcium and chlorine?

(iii)      Give two properties of the bond you have mentioned in (ii) above.

(b)      Define the following terms as applied in Chemistry

(i)  Decantation

(ii) Filtration

(iii)    Picking

(iv)     Funnel Separation

(c) (i)Which is the most abundant element on the earths outer crust? (ii) The term used for acidic chemicals which can burn your skin is

(iii) Give the name of a flame which forms soot .........

9.     (a) Explain why:

(i)      a magnesium ion has a charge of 2+ .........

(ii)   a magnesium oxide has no overall charge ..

(b)       Give the name of a bond which can be formed between two oxygen atoms .......

(c)      (i) State the modern periodic law

(ii)      Give the special name for each of the following groups of elements in the periodic table:

Group I .........

Group Vll .........

(iii)    Why is the atomic number a better way of identifying an element than the mass number? .

10.                    (a) Mention four physical properties of water.

(b)      What will happen when:

(i)       a burning splint of wood is introduced into a gas jar containing oxygen gas

(ii)     oxygen gas reacts with metals .

(iii)   hydrogen gas reacts with oxygen gas .........

(c)      List four uses of hydrogen in our daily life.

YEAR : 2011  SUBJECT : CHEMISTRY

(i) Isotopes are atoms of the same element that have different:

  1.  Atomic number 
  2.  Electron arrangement
  3. Mass number 
  4. Protons

 (ii) When substance A and substance B react to produce a new substance C, the reactants A and B are said to:

  1. Be miscible 
  2. Form a mixture
  3. Form a solution C
  4. Undergo chemical change

 (iii) In the formula of the compound F2K3 the valences of F and K are respectively:

  1. 2 and 3 
  2. 3 and 2
  3. 4 and 6 
  4. 6 and 4

 (iv)  The process by which water is converted into water vapour or steam is called:

  1. Condensation
  2. Evaporation
  3. Precipitation
  4. Transpiration

 (v) In the Bunsen burner a sooty flame is most likely to be formed when the:

  1. Air holes are fully closed 
  2. Air holes are opened
  3. Flame is noisy
  4. Flame is smaller and hotter

 (vi)  The best way to separate a mixture of iodine and iron fillings is by:

  1. Decantation
  2. Evaporation to dryness 
  3. Ractional distillation
  4. Sublimation

 (vii) The choice of the source of heat depends on the:

  1. Colour of the flame
  2. Quantity of heat produced
  3. Substance to be burned or boiled
  4. Type and shape of flame

 (viii) When oxygen combines with metals they:

  1. Form metallic oxides 
  2. Form precipitates 
  3. Rust
  4. Sublime

 (ix)  The pair elements which is most likely to form a covalent bond when  they react together is:

  1. Carbon and oxygen
  2. Magnesium and potassium
  3. Nitrogen and aluminium
  4. Sodium and oxygen

 (x) A calcium ion (Ca2+) differs from calcium atom (Ca) because a calcium ion has:

  1. Less electrons
  2. Less protons
  3. More electrons
  4. More neutrons

2. Match each item in List A with a response in List B by writing its letter against the corresponding item.

LIST A

 LIST B

(i) Burning gases that give out heat and light

(ii) Coating iron objects using zinc metal

(iii)    Domestic water treatment and purification

(iv)     Heterogeneous mixture

(v)      Holds maximum of 8 electrons

Intelligent guess on the cause of the problem

(vii) Liquid metal

(viii)Relights a glowing splint

(ix)    The burning material is a liquefied gas

(x)      Turns white anhydrous copper

(Il) sulphate blue

A.    Boiling and filtration

B.    Class C fire

C.    Distillation

D.    Energy shell 1

E.     Energy shell 2

F.     Experimentation

G.     Flame

H.    Galvanization

I.      Hydrogen

J.      Hypothesis

K.   Mercury 

L.   Oxygen

M.   Solution

N.    Suspension

O.   Water

      











SECTION B

3.    (a) Why do atoms combine?

(b)     A metal Z atomic number 12 combines with chlorine to produce a metal chloride. By means of diagrams illustrate the arrangement of electrons in Z before and after the reaction.

(c)     An atom X of atomic number 14 combines with chlorine to form a chloride. What type of bond will be formed between the atoms?

4           What do you understand by the term "valency"?

(b) Calculate the oxidation number of the underlined elements: (i) NaOH

(ii) CO32-

(iii) Na3P04

(v) S02

(c) Explain three points on the importance of changing one state of matter to another.

5.          Give two reasons why water is a compound.

(b) Write IUPAC names for each of the following compounds: (i) CaC03

(iii) NaHC03

(iv) )2

(v) KCl

(c) Describe a chemical test for water.

6.          State the law of conservation of energy.

(b)      Give two ways in which energy can be transformed from one form to another.

(c)       List down two sources of heat in the laboratory.

7.         (a) Define the term "empirical formula".

(b) An organic compound contains 26.7% carbon, 2.2% hydrogen and 71.1% oxygen. If its relative molecular mass is 90, determine its:

(i)         Empirical formula

(ii)       Molecular formula

(c) State three points of modern atomic theory that amend Daltons ideas.

8.         (a) Differentiate between:

(i)         an atom and an element

(ii)       Combustion and rusting

(iii)      a solute and a solvent

(iv)      a compound and a mixture

(b) Give two applications of chemistry in everyday life

(c)  Why most laboratory apparati are made of glass?

9.         Below is part of the periodic table and the numbers represent atomic numbers. Study the table carefully then answer the questions that follow:

Write T in the space where a noble gas in period 3 would occupy. Write U in the space where the most active metal would occupy.

(iii) Write W in the space where the most active non-metal would occupy.

Write X in the space which would be occupied by an element in period 3 capable of forming a compound XW

(v) Write Y in group Il period 4 element.

 Write Z in group VI period 3 element.

(b)     Write the chemical symbols of the following elements:

(i)       Argon

(ii) Sulphur

(iii)    Boron

(iv)     Silicon

(v)      Phosphorus

(c)      Write the formula of each compound formed between:

(i)       Aluminium and chlorine

(ii)     Potassium and oxygen

10.  (a) (i) Name two reagents normally used for preparation of hydrogen in the laboratory.

(ii) Write a word equation for the reaction in (i) above.

(b)      (i) Why is hydrogen gas used for filling balloons? (ii) Describe chemical test for hydrogen gas.

(c)      Explain safety measures that should be taken when handling chemicals with the following warnings:

       (i) Flammable

(ii)     Corrosive

(iii)   Irritant or Harmful

(iv)   Toxic

YEAR : 2010  SUBJECT : CHEMISTRY

(i) In scientific study, the tentative explanation for the observed chemical phenomenon can be proved by:

  1. Data analysis
  2. Experimentation
  3. Hypothesis
  4. Observation

 (ii)   A certain liquid dissolves copper (Il) sulphate to form a blue solution. This liquid is likely to be:

  1. Hydrochloric acid
  2. Liquid oxygen
  3. Nitric acid
  4. Water

  (iii)   When a chemist studies a substance he/she is interested in its:

  1. Force of attraction
  2. Properties
  3. Shape
  4. Smell

 (iv)  The boiling point of pure water at sea level is 1000C and that of ethanol is 780C. The mixture of ethanol and water can be separated by:

  1.  Filtration process
  2. Fractional distillation process
  3. Layer separation process
  4. Sublimation process

 (iv)  The boiling point of pure water at sea level is 1000C and that of ethanol is 780C. The mixture of ethanol and water can be separated by:

  1.  Filtration process
  2. Fractional distillation process
  3. Layer separation process
  4. Sublimation process

 (vi)   Which group among the following elements are metals?

  1.  Calcium, magnesium and sodium
  2. Calcium, hydrogen and nitrogen
  3. Calcium, carbon and magnesium
  4. Oxygen, potassium and sodium

 (vii)  An electrovalent bond is formed by:

  1. Arrangement of electrons
  2. Sharing of electrons
  3. Transfer of electrons
  4. Vibrations of electrons

 (viii) Petrol is an example of:

  1. Corrosive substance
  2. Flammable substance
  3. Irritating substance
  4.  Toxic substance

 (ix)    The electronic configuration of silicon is:

  1. 2:7:3
  2. 2:8:2
  3. 2:8:3
  4. 2:8:4

 (x)  The most abundant element on the earth is:

  1. Carbon
  2. Iron
  3. Nitrogen
  4. Oxygen

(viii)   Petrol is an example of:

  1. corrosive substance          
  2.  flammable substance 
  3. irritating substance  
  4. toxic substance

(ix)     The electronic configuration of silicon is:

  1. 2.7.3
  2. 2.8.2
  3. 2.8.3
  4. 2.8.4

(x)       The most abundant element on the earth is:

  1.  carbon  
  2. iron
  3.  nitrogen                 
  4. oxygen

SECTION B

2. You are provided with two lists, A and B. Choose a word(s) from list B which matches the statement or phrase in list A and write down its letter.


LIST A


LIST B

(i)        Addition of hydrogen to a substance or removal of oxygen from a substance

(ii)      A way by which atoms become stable

(iii)    Coating • iron objects using zinc metal

(iv)     Modern scientific procedure

(v)      Environmental friendly fuel

(vi)     Method used to extract oil from nuts

(vii)   Speeds up the rate of chemical reaction

(viii)Used for grinding solid chemicals

(ix)     Used in making electric bulb signs

(x)      Substance which can burn your skin

A.       Biogas

B.          Bonding

C.          Catalyst

D.          Corrosive

E.          Data analysis

F.          Desiccator

G.          Galvanization

H.          Irritating

I.            Noble gases

J.           Mortar and pestle

K.          Painting

L.          Reduction

M.         Solution extraction

N.          Solvent extraction


SECTION C

3.          (a) (i) Explain what you understand by the word fuel.

(ii) Name the state of matter under which the following fuels belong:

Kerosene

Charcoal

Biogas 

(b) Give two reasons to explain why non-luminous flame is normally used as a source of heat in the laboratory.

(c) (i) Define the term rust.

(ii)      Mention conditions necessary for iron rusting.

4.          (a) What do you understand by the following terms?

(i)        First Aid

(ii)      First Aid kit

(b)      Name four components which can be found in a First Aid kit.

(c) Why is it important to provided First Aid to an injured person? (Give four reasons)

5.          (a) A sample of chlorine gas contains 75% of 17Cl35 isotope and 25% of isotope 17 Cl37. What is the relative mass of chlorine atom?

(b)      For each of the following indicate whether the process is a chemical or physical change:

(i)        Burning of a candle ............

(ii)      Decaying of meat 

(iii)    Souring of milk ............

(iv)     Dissolution of common salt in water ............

(v)      Sublimation of iodine from the mixture of iodine and sand ............

6.          (a) What do you understand by the term element?

(b)      Write a chemical symbol for each of the following elements: (i)Iron .........  (ii) Silver .........

(iii)    Gold . 

(iv)     Sodium ......... (v) Helium .........

(c)       Write down four substances which produce energy when burnt.

7.          (a) If a mixture of manganese (IV) oxide, Mn02 with potassium chlorate. KCl0is heated, which of the two compounds will produce oxygen?

(ii) Why? . 

(b)      Calculate the oxidation number of the underlined elements.

(ii)      KC103

(iii)    NH4+

8.          (a) List down four assumptions of the Daltons Atomic Theory

(b)      Write a chemical formula for each of the following compounds:

(i)      Water 

(ii)   Potassium chloride  

(iii)Magnesium oxide 

(iv)Calcium hydroxide 

(c) (i) What do you understand by the term "chemical warning signs"?

(ii)      Draw the chemical warning sign that represents:

  •        Harmful Or Irritant
  •        Toxic
  •        Flammable

9.          (a) Write down the method which can be used to separate the following mixtures:

(i)        Sand and rice 

(ii)      Crude oil 

(iii)    Iron filings and table salt 

(iv)     Muddy water 

(v)      Chlorophyll from green leaves 

(b)      List down two uses of hydrogen gas in our daily life:

(c) Give three places or areas where the knowledge of Chemistry can be applied:

10.      (a) List down three sources of natural water.

(b)      Explain why water is not used to extinguish class E fires.

(c) Give a reason to support the following facts:

(i)Oxygen gas is collected over water.

(ii) Water is a universal solvent.

(iii)Group (VIII) elements cannot form compounds.

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