THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATIONS COUNCIL OF TANZANIA
FORM TWO NATIONAL ASSESSMENT
032 CHEMISTRY
Time: 2:30 HoursYear: 2020
Instructions
1. This paper consists of sections A and B with a total of ten (10) questions.
2. Answer all questions in the spaces provided.
3. Section A carries twenty (20) marks and section B carries eighty (80) marks.
4. All writing must be in black or blue ink except diagrams which must be in pencil.
5. Cellular phones and any unauthorised materials are not allowed in the assessment room.
6. Write your Assessment Number at the top right corner of every page.
7. The following atomic masses may be used: H = 1, N = 14, 0 = 16, S = 32, Ca = 40.
SECTION A (20 Marks)
Answer an questions in this section.
I .For each of the items (1) (x), choose the correct answer from among the given alternatives and write its letter in the box provided.
(i) The net charge inside the nucleus of an atom is contributed by
(ii) Why oxygen as one of the components of air is unique?
(iii) Which material is not involved in respiration?
(iv) Which element causes permanent hardness of water when combined with sulphate?
(v) Carbon dioxide. Oxygen, Nitrogen and Hydrogen Sulphide are
(vi) Which common feature is associated with elements of the same group?
(vii) The oxidation state of metallic elements is always
(viii) An isotope of Lead with atomic number of 82 and mass number of 207 has
(ix) Which conditions are necessary for iron nails to rust?
(x) Which decision should be made if the results of an experiment do not support the stated hypothesis?
7. (a)Why is petrol not recommended to be used as fuel in school laboratories? Briefly explain.
(b) Which three heat sources can be used to boil some water in the laboratory instead of the Bunsen burner?
(c) Arrange the following steps for lighting the Bunsen burner in a correct sequence using letter
A to F.
Answer
Step | 1 | 2 | 3 | 4 | 5 | 6 |
Letter |
8. (a)Giving a reason, state whether rust will form or not in each of the situations (i) - (vi).
(b)Briefly explain any four methods of preventing rusting.
9(a)Write chemical formulae of the two compounds from which oxygen gas can be prepared by decomposition.
(b)What are the three physical properties of oxygen gas?
(c) Why is it important to have abundant oxygen gas on the Earth? Give five reasons.
10. Identify the five accidents which are common in the laboratory and in each explain possible causes and preventive measures to be taken.
2. (a)Match each item in List A with a correct response in List B by writing the letter of the correct response below the corresponding item number in the table provided.
List A | List B |
(i) An element with atomic number (ii) The type of bonding which occurs between non metals. (iii) Elements in the Periodic Table found in groups IV to VII. (iv) Vertical columns of the Periodic Table. (v) Elements which react vigorously with water |
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(b) Answer the given questions by writing the correct answer in the blank spaces provided.
(i) In which stage is the hypothesis tested during scientific investigation? . . . . . . . . . . . . . . . . .
(ii) On which factor does the physical state of a molecule depend? . . . . . . . . . . . . . . . . .
(iii) Which properties depend on the proportions of mixing substances in a mixture? . . . . . . . . . . . . . . . . .
(iv) What are the building blocks of matter? . . . . . . . . . . . . . . . . .
(v) Which particles are transferred during chemical reactions? . . . . . . . . . . . . . . . . .
SECTION B (80 Marks)
Answer all questions in this section.
3. (a) Why candles are not suitable for heating in the laboratory? Give two reasons.
(b) Differentiate luminous from non-luminous flame by giving five points.
4. (a) State four main ideas of the Dalton's atomic theory of matter.
(b)Classify each of the following elements into their respective groups and periods.
SIN | Element | Group | Period |
(i) | Calcium |
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(ii) | Hydrogen |
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(iii) | Chlorine |
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(iv) | Boron |
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(v) | Aluminium |
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5. (a)With an example for each, give two fields in which the scientific procedure is applied.
(b) Categorize the three factors (variables) which affect the problem being investigated during scientific investigation.
6, (a) Briefly explain why:
(i) the use of charcoal is harmful to the environment.
(ii)charcoal is still being used by majority of Tanzanians for domestic purposes.
(b) A mass of 20.0 g of petrol was burnt in air. The heat produced was used to heat 2.5 litres of water. Given that the heat value of petrol is 43,640 kJ/kg, by how much the temperature of water could have changed? (The specific heat capacity of water = 4.18 Id kg-1 K-1, Density of water = 1000 kg/m3).
(c) Arrange the following steps for lighting the Bunsen burner in a correct sequence using letter
A to F.
THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATIONS COUNCIL OF TANZANIA
FORM TWO NATIONAL ASSESSMENT
032 CHEMISTRY
Duration: 2:30 Hours
INSTRUCTIONS.
SECTION A (20 Marks)
Answer all questions in this section.
1. For each of the items (i) –(x), choose the correct answer from the among the given alternatives and write its letter in the box provide.
(i) What is the best way of keeping a clean test tube after use?
(ii) Which one of the following does not involve the processes of urban water treatment and purification?
(iii) Why hydrogen gas is not a constituent of air?
(iv) Which is the suitable alternative heat source to be used in absence of Bunsen Burner?
(v) Which group and period does the element with 11 electrons belong?
(vi) What happens when substance A reacts with substance B to form a new substance C?
(vii) Which components make fire triangle?
(viii) Which state is involved when drying wet clothes?
(ix) Which net charge exists in radicals?
(x) Why Non – luminous flame is the most applicable flame for heating purposes?
2. (a) Match each item in List A with a correct response in List B by writing the letter of the correct response below the corresponding item number in the table provided.
List A | List B |
(i) A solvent which dissolves most substances to form solution. (ii) A substance that has no definite shape or size. (iii) A substance that has a fixed shape and volume (iv) A substance whose components can be separated by physical means (v) Homogeneous mixture of two or more substances. |
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(b) Fill in the blank spaces by using the appropriate terms
(i) In an atom, the effect of the charged nucleons is balanced by the charge of……………..
(ii) Serum is separated from blood samples by employing a technique called………………..
(iii) Boiling points of substances reflect the strength of……………….
(iv) Grinding chalk into a powder involves changing the state of …………………….
(v) The insoluble substances formed during filtration are collectively termed as ……………….
SECTION B (80 Marks)
Answer all questions in this section.
3. (a) State one use of each of the items (i) – (x) in administering First Aid.
S/N | Item | Use |
(i) | Soap |
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(ii) | Bandage |
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(iii) | Sterile gauze |
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(iv) | Iodine tincture |
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(v) | Petroleum jelly |
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(b) Give one function of each of the following apparatus in the chemistry laboratory.
(i) Spatula…………… …………… ……………….
(ii) Gas jar…………… ……………. …… ……….
(iii) Lie – big condenser …………… …… …………
(iv) Motor and pestle…… …………… …………… (v) Wire gauze… ………… ………… ……………. 4. (a) By giving one reason, explain the following facts. (i) During laboratory preparation of oxygen gas, little manganese dioxide is added to hydrogen peroxide ………… ………… ……… …………… ………… ……… …………… …………… (ii) Fish can obtain oxygen for respiration although spend their lives in water. …………… …………… …………… ………………… …….......... ....... .... (iii) Oxygen gas can be used for welding activities although it does not burn. ……………… ……………… …… …………… ……………………… (b) Which property enables the use of hydrogen gas in: (i) Filling weather balloons? ……………… ………………… ……… ……… (ii) Production of oxy – hydrogen flame? ………… ………… ………………………… …. (c) Give two domestic uses of oxygen gas. (i) ……………… ……………………… (ii) ……………… ……………………… 5. (a) Give three chemical tests for water and show the results obtained in each. (i) ………… …………… ………………… (ii) ………… ……………… ……………… (iii) ………… ……………… ……………… (b) (i) Differentiate water treatment from water purification. ……… ……… ……………… … ……… ……… … ……… ……… (ii) Why drinking water should be treated and purified? Give two reasons. (i) ………………… ………………… …… (iii) How can drinking water be treated or purified? (i) ………… …………………… …… …. (ii) …………… ……………… ……… …. (iii) … ……… ………………… ……… …. 6. (a) Differentiate hypothesis from analysis. …………… ………………… …… ……… …………………… ……… (b) Effective use of the four senses of observation is important before a chemist can make conclusion. With four points, show how the senses are used as tools of observation during experimentation by giving one example for each. (i) ………… ………… …………… (ii) ………… …………… …………. (iii) ………… ……………… …… …. (iv) ………… …………… …………… 7. What precautions will you take in handling chemicals having the warning signs shown in the table? Give two precautions in each sign. S/N Sign Relevant Precaution a) (i) ………… ……… …………… …. (ii) ………… ………… ……………. b) (i) …………… …………… …. (ii) ………… ………… …… …. c) (i) …… …………… ……………. (ii) ……… …………… …………. d) (i) …………… ……………… ……. (ii) …………… ………… …………. e) (i) …………… ……… ……………. (ii) …………… …………… ………. 8. Briefly explain the five classes of fires based on the nature of the burning material and the extinguisher required. Give one example for each class. a) ……… ………… ………………… ………………… b) …………………… ………………………… ……… 9. A certain gaseous compound contains 30.4% of nitrogen and 69.6% of oxygen by mass. If the molar mass of the compound is 92, calculate its molecular formula. Stage Nitrogen Oxygen ………………… ………………… ……………… ………………… …………………… …………… …………………… …………………… ………… 10. Briefly explain five characteristics to be considered when looking for a good fuel. (i) ………………… ………………… (ii) ………………… ………………… (iii) ………………… ………………… (iv) ………………… ………………… (v) ……………… …………………… (i) Chemistry is a branch of Science which deals with: (iii) Which of the following are the main components of a fire triangle? (iv) The process of removing solid contaminants from water is known as: (v) How many zones are there in a non-luminous flame? (vi) The process of coating iron or steel with zinc is known as: (vii) A certain element has atomic number W and mass number Y. The number of neutrons contained in its nucleus is: (viii) When a small amount of sugar is dissolved in a glass of water the mixture formed is: (ix) Fainting is a sudden loss of: (x) Why is fractional distillation of coal done? THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATION COUNCIL CHEMISTRY FTNA 2018 (i) Chemistry is a branch of Science which deals with: (ii) Which of the following are the states of matter? (iii)Which of the following are the main components of a fire triangle? (iv)The process of removing solid contaminants from water is known as: (v)How many zones are there in a non-luminous flame? (vi)The process of coating iron or steel with zinc is known as: (vii)A certain element has atomic number W and mass number Y. The number of neutrons contained in its nucleus is: (viii)When a small amount of sugar is dissolved in a glass of water the mixture formed is: (ix)Fainting is a sudden loss of: (x)Why is fractional distillation of coal done? 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. (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. (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 are 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 (b) Give four importance of First Aid. 4.Draw and give one function of the following apparatus: Apparatus (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.(a) 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 questions that follow: (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.(a) 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 (i) Which statement gives a clear meaning of Chemistry? (ii) The mass number of an atom is determined by: (iii)Which of the following is a metal? (iv)Air entering the Bunsen burner barrel can be controlled by (v) How many atoms are there in a water molecule (vi)Which neutral atom has the same number of eletrons as Mg2+? (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: (viii) A non-luminous flame is obtained if the hole is: (ix)Which is the least abundant gas in the air? (x) The process which produces energy in form of heat and light is called: THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATION COUNCIL CHEMISRY FTNA 2016 (i) Chemistry is defined as: (ii) A non-luminous flame is the most applicable flame for heating purposes because: (iii) Matter is defined as anything that has: (iv) Which of the following process is used in preventing rust of an iron? (v) Water is a universal solvent because: (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. (vii) Class F fire can best be extinguished by using (viii)Which of the following components can be separated by filtration method? (ix) Which of the following is the colour change when cobalt chloride paper is used to test the presence of water? (x) All domestic utensils made of iron undergo rusting when exposed to 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 A LIST B A. Atomic number B. Electron C. Radical D. Metalloids Isotopes E. Mass number F. Neutron G. Allotropes H. Noble gases I. Period J. Group K. Proton L. Valence Atomic radii M. Halogens
Which of the following are the states of matter?
LIST A LIST B
Meaning (i) (ii) (iii) (iv)
Drawing Function
Element Atomic Mass Atomic Number F 16 8 G 19 9 L 23 11 M 12 6 J 20 10