LEARNING HUB.TZ

CHEMISTRY EXAMINATION FORM TWO

TOPICAL EXAMINATIONS.

OXYGEN

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, B and C

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

SECTION A

1. Question (i) – (x) are multiple choice items write down the letter of the correct answer:-

1. A mixture of two solid substance is commonly heated in the laboratory to produce oxygen such mixture could be that of:-

1. Manganese dioxide, hydrogen and magnesium

2. Potassium permanganate and magnesium oxide

3. Mercury (ii) oxide and hydrogen peroxide

4. Potassium chlorate and manganese (iv) oxide

2. The sold manganese (iv) oxide which is used in the preparation of oxygen using hydrogen peroxide play the role of :-

1. An oxygen producer

2. An oxidant

3. A catalyst

4. A- reducing agent

3. When oxygen is prepared in the laboratory it usually collected by

1. Downward delivery

2. Displacement of air

3. Up delivery

4. Displacement of water

4. Fish and other aquatic organism breathing in oxygen which is

1. Combine with water

2. Present in the water molecule

3. So- plentiful in the air

4. Dissolved in water

5. The natural process which supplies oxygen to atmosphere is

1. Respiration

2. Combustion

3. Breathing

4. Photosynthesis

6. The metal known to produce hydrogen from dilute nitric acid is :-

1. Magnesium

2. Aluminium

3. Iron

4. Lead

7. Which of the following sets of process in present uses of oxygen gas:-

1. Welding, ice melting , magnetization

2. Mountaineering, sublimation, freezing

3. Glass cutting, desiccation, welding

4. Diving, welding , mountaineering.

8. Hydrogen gas can be collected by downward delivery because

1. It burns in air with a pop sound

2. It is more soluble than air

3. It is lighter than air

4. It can fill balloons

9. When oxygen combine with metals they

1. Form basic oxides

2. Form acidic oxide

3. Rust

4. Sublime

10. Which of the following is not true about hydrogen:-

1. It is lighter than air

2. It burns with blue flame

3. It is support combustion

4. It is odor less.

SECTION B

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

LIST A	LIST B
Relights a glowing splint Additional of hydrogen to substance or remove of oxygen from a substance Pop sound Liquid metal Speed up the rate of chemical reaction Condition for iron to rust Oxygen is used burn food to produce energy carbon dioxide and water Burn in oxygen to produce acidic oxides The metal which may liberate hydrogen from hydrochloric acids Burn in oxygen to produce basic oxide.	Breathing hydrogen gas oxygen gas reduction catalyst oxidation water and kerosene respiration presence of water and oxygen mercury metals zinc non metals carbon dioxide chemical change

SECTION C

3. List four (4) chemical properties of oxygen

4. Write three (3) common methods of preparations of oxygen in the laboratory

5. What is chemical test for oxygen gas?

6. List any four (4) uses oxygen gas in our daily life

7. Write a word chemical equation to show the decomposition of hydrogen peroxide in the presence of manganese (IV) oxide.

8. Why oxygen gas is collected over water?

9. Respiration and burning are similar process in some ways and difference process in other ways. Give two differences between them.

10. Consider the diagram below and then answer the questions that follows:

Label parts

1. A ………………………………………………………………………………………

2. B…………………………………………………………………………………………

3. C…………………………………………………………………………………………

4. D ………………………………………………………………………………………

E ……………………………………………………………………………………………..

LEARNING HUB.TZ

CHEMISTRY EXAMINATION FORM TWO

TOPICAL EXAMINATIONS.

HYDROGEN

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, B and C

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

1. SECTION A 20 MARKS

MULTIPLE CHOICE QUESTIONS

1. Which one of the following statements about hydrogen is wrong?

1. Air and pure hydrogen mixture explodes spontaneously

2. Hydrogen does not support combustion although it’s a good fuel

3. water is the oxide of hydrogen only

4. 100% pure hydrogen gives a ‘pop’ sound with a burning splint.

2. What type of displacement is done by collecting pure hydrogen in the laboratory;

1. Downward displacement of water

2. Downward displacement of air

3. Upward displacement air

4. Upward displacement of air

1. The best reagents used in preparation of hydrogen gas in the laboratory include;

1. Copper foil with dilute sulphuric acid

2. Sodium metal with concentrated sulphuric acid

3. Zinc powder with dilute nitric acid

4. Zinc granules with dilute hydrochloric

4. Which of the following gases if mixed with hydrogen produce a very hot flame or up to 3000 ⁰c.

1. Oxygen

2. Neon

3. Chlorine

4. Argon

4. Which of the following is not a property of Hydrogen gas?

1. It support combustion

2. It is slightly soluble in water

3. It is less denser than air

4. It is colorless and odorless

4. Which two chemicals are used to dry hydrogen?

1. Zinc and hydrochloric acid

2. Calcium chloride and concentrated sulphuric acid

3. Sodium hydroxide and steel wool

4. Copper (II) oxide and anhydrous copper (II) sulphate

5. Which one of the following methods can easily be used to get hydrogen in the laboratory?

1. Fractional distillation of liquid air

2. Capturing of air in a gas jar

3. Mineral acid reacted with moderately reactive metal

4. All of the above.

5. Which one of the following method can easily be used to distinguish hydrogen from oxygen in the laboratory?

1. A burning splint acquires a brighter flame in oxygen and ‘pop’ sound in hydrogen

2. Oxygen is a bit more soluble in water than hydrogen through very slight

3. Oxygen is of a higher density than hydrogen

4. Hydrogen boils at - 253_ while oxygen boils at - 183_

5. Which one of the following statements is wrong about oxygen and hydrogen?

1. Hydrogen supports combustion while oxygen burns

2. Many substances burn in oxygen to include hydrogen which produces a blue flame

3. A right mixture of oxygen and hydrogen explodes when the kindling temperature of hydrogen is reached

4. Oxygen or hydrogen does not change a clamp litmus paper

5. What is the right message obtained from the equation: hydrogen + oxygen → water

1. Study of physical properties of hydrogen and oxygen

2. Study of chemical properties of hydrogen and oxygen

3. Laboratory test for oxygen

4. Laboratory preparation of oxygen and hydrogen

5. Hydrogen gas can be collected by downward delivery because:

1. It burns in air with a pop-sound

2. It is more soluble than air

3. It is lighter than air

4. It can filled balloons

5. One method among the following is the industrial method for preparation of hydrogen:-

1. From water by hot carbon

2. From acids by using moderately reactive metals.

3. The action of manganese(IV)oxide on hydrogen peroxide

4. Both A, B and C are correct

2. Matching item questions: Select the most correct answer from list B that matches with the statement in List A.

>

LIST A

LIST B

………… is added in the water for aim of killing micro – organisms present in water. ………….. burns in oxygen to form its oxide. React with HCl to form Hydrogen Hardening of oils into fats using hydrogen Product of burning hydrogen in air Removal of hydrogen from a substance Manufacture of ammonia It re – kindle a glowing splint. ……… is lighter than air that is why it is used in filling balloons. ……….. is produced when hydrogen burnt in air.

Pop sound Chlorine Zinc Contact process Haber process Oxidation Reduction copper Fluorine Metal or non – metal Hydrogen hydrogenation Oxygen Helium

2. Gas “P” has the following properties; it is highly flammable, readily combines with other elements, readily reacts with other chemical substance and is a strong reducing agent.

1. Name the gas “P”

2. What is the method used to collect gas “P” in the laboratory? Give reason

3. Give four (4) uses of gar “P”.

2. Draw a well labeled diagram to show how dry hydrogen can be made in the laboratory (join all parts of the apparatus in your diagram)

3. (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 is used for filling balloons?

(ii)Describe chemical test for hydrogen gas.

2. (a) Which property of hydrogen leads to the following uses of it?

>

Use	Property
Oxy – hydrogen flame Weather balloons Manufacture of margarine	………………………………………………………. ……………………………………………………….. ……………………………………………………….

b)Complete the following statement.

When …………………… gives a ‘pop’ sound with a ………………….. splint, oxygen ……………………………. a …………………….. splint.

2. (a) Name two reagent normal use for preparation for hydrogen in the laboratory

(b)Write the word equation for reaction above

(c)Describe the chemical test for the hydrogen gas

(d) Why hydrogen used for fillings balloon?

2. (a) Gas jar B was full of hydrogen gas while gas jar A was full of Air;

Gas jar A

Air

Dry hydrogen

Gas jar B

1. What do you notice after putting a burning splint in gas jar A after some time. 02 marks

2. What conclusion can you draw about the density of hydrogen gas? 0marks

(b) State the products formed when the following elements are burn is oxygen combine with

oxygen;

1. Carbon …………………………………………………………………………

2. Copper …………………………………………………………………………

3. Zink ……………………………………………………………………………

4. Hydrogen ………………………………………………………………………05 marks

LEARNING HUB.TZ

CHEMISTRY EXAMINATION FORM TWO

TOPICAL EXAMINATIONS.

WATER

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, and B

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

1. SECTION A 20 MARKS

1. Which is the quick distinguishing chemical characteristic of water?

1. Its boiling point is 100°C.

2. Its density of 1g/cm³

3. It is colorless liquid

4. It changes white copper (II) sulphate to blue.

2. Sea water contains various salts. Which one is present in the largest proportion?

1. Calcium sulphate

2. Sodium chloride

3. Magnesium chloride

4. Magnesium sulphate

3. Which one of the following represent the chemical combination of substances result into the formation of water;

1. M agnesium + oxygen Magnesium oxide.

2. L ead (II) Oxide + Hydrogen Lead + water

3. H ydrogen + Oxygen Water

4. S ilver oxide + Hydrogen Silver + Water

4. Which one is not physical property of water among the following;

1. Water is colourless, odourless and taste loss liquid

2. Water react with reactive metals producing alkali solution and hydrogen gas

3. Water is a good solvent for many substance

4. Pure water has 1g/cm3 and 760mm of Hg.

5. The process of chlorination in water treatment aims at;

1. Making syrup

2. Removing bad odour

3. Killing micro – organisms [ ]

4. Forming suspension

6. The process of chlorination in water treatment aims at:-

1. Killing micro organisms

2. Syrup making

3. Forming suspension

4. Removing bad odours

7. A certain liquid dissolves copper (II) sulphate to form blue solution. This is likely to be:-

1. Hydrochloric acid

2. Liquefied oxygen

3. Water

4. Nitric acid

8. For what reasons is water important to living things?

1. Production of H.E.P

2. Preparation of drinks.

3. Warning utensils

4. Medium of transporting nutrients

9. Which are the ways by which bacteria in the water are put under control during water works;

1. Exposure of water mass to sunshine

2. Growth of slime plants on sand filters

3. A creation and chlorination of filtered water

4. All of the above.

10. What is the use of the Deionizer plant?

1. To produce ultra pure water

2. To produce distilled water

3. To produce water filtrate

4. none of the above

11. What is another name used for potable water?

1. Distilled B. Hard C. Drinking D. Soft

12. Which of the following statements is correct?

1. Purified water does not contain dissolved oxygen

2. Treated water is not necessarily pure but pure water is treated water.

3. Treated water is distilled water

4. Treated water is also pure water

13. When elements Aluminium, Calcium, Sodium and Potassium are studied for reactivity with water which one is the least reactive?

1. Potassium B. Calcium C. Sodium D. Aluminium

14. What can one arrive at from observational changes of the density of water which take place between <4°C to>4°C

1. Water has large heat capacity

2. Water is a universal solvent

3. Water expands non – linearly

4. Water exhibits surface tension.

15. The following main parts of hydrological cycle are orderly arranged;

1. Evaporation, condensation, precipitation and collection

2. Condensation, precipitation, collection and evaporation

3. Precipitation, collection, evaporation and condensation

4. Collection, evaporation, condensation and precipitation

16. Which other processes serves the hydrological cycle in the same way as evaporation?

1. Drying and respiration

2. Burning and transpiration

3. Anyone which rises humidity in the air

4. All of the above

2. Matching items questions.

3. (a) Define the term;

1. Water ………………………………………………………………………………………………………………………………………………………………………….

2. Water cycle ……………………………………………………………………………………………………………………………………………………………………..........

(b) List four important processes involved in the circulation of water;

1. ………………………………………………………………………………………

2. ………………………………………………………………………………………

3. ………………………………………………………………………………………

4. ……………………………………………………………………………………..

4. (a) Write the names of chemical substances used to test the presence of water;

1. ……………………. and ii ……………………………

(b) Write the examples in which water occur as;

i. Solid ……………………………………………………………………………

ii. Gas ………………………………………………………………………………

(c) Name chemical substance used in laboratory preparation of hydrogen gas ………………………………………………………………………………………………

5. (a) List down three (3) 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

1. Water is universal solvent

2. Oxygen is collect over water

3. Oxy-hydrogen used in welding

6. (a) Give two reason why water is a compound

(b)Describe the chemical test for water

(c ) Give reason to support the fact “water is universal solvent”

7. (a) Define the following terms;

1. Water treatment ………………………………………………………………………………………………………………………………………………………………………………

2. Water purification …………………………………………………………………………………………………………………………………………………………………………………

(b) Name impurities that can be found in water?

1. …………………………………………………………………………

2. …………………………………………………………………………

3. …………………………………………………………………………

4. …………………………………………………………………………

(c) State any two methods of domestic water treatment;

(i) ……………………………………………………………………………..

(ii) …………………………………………………………………………….

8. (a) If the % mass of salt water on the earth is 97 and of all salts common salt take up 75. (i) What is its % on the earth? (ii) What part remains for other salts?

1. __________________________________________________________________

2. __________________________________________________________________

(b) The four types of natural water are:

(i) _______________________________________________

(ii) _______________________________________________

3. ________________________________________________

4. ________________________________________________

LEARNING HUB.TZ

CHEMISTRY EXAMINATION FORM TWO

TOPICAL EXAMINATIONS.

FUEL AND ENERGY

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, and B

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

1. SECTION A 20 MARKS

1. MULTIPLE CHOICE QUESTIONS

1. Which one of the following energy transformation can produce H.E.P?

1. Electrical energy changes to heat energy

2. Electrical energy changes to mechanical energy

3. Mechanical energy changes to Electrical energy

4. Mechanical energy changes to chemical energy

2. 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

2. ___________is the characteristic of good fuels:-

1. Firewood

2. Easily available

3. Melting

4. Ability to burn houses into ashes.

2. What is kindling temperature

1. A kind temperature

2. Temperature out of a burning material

3. The highest temperature obtained from a burning substance

4. The lowest temperature at which a combustible material can catch fire.

2. Which of the following is a renewable source of energy?

1. Coal

2. Petroleum

3. Biogas

4. Natural gas

2. Which of the following is not a primary source of energy?

1. Wood

2. Kerosene

3. Crude oil

4. Natural

2. Which of the following is not a characteristic of a good fuel?

1. Readily available

2. Should have low energy value

3. Should be affordable

4. Easy to transport

2. In production of hydroelectric power, which of the following is the best energy transformation?

1. Electric energy to heat energy

2. Electrical energy to mechanical energy

3. Mechanical energy to electrical energy

4. Chemical energy to electrical energy

2. Which of the following has a chemical energy?

1. Natural gass

2. Biomass

3. Coal

4. Solar energy

2. Which of the following is not an advantage of biogas?

1. It is cheaper source of energy

2. Pollutes the environment

3. It is renewable source of energy

4. Creates employment among the youth

2. Matching items questions

1. Electricity can be used to perform work also for heating purpose. Explain how it can happen and use four (4) practical examples in each case.

2. (a) What is fuel? ……………………………………………………………………………………………………………………………………………………………………………………………………

(b) Mention three categories of fuel and give two examples for each category.

(i) ………………………………………..

examples …………………………………. and ………………………………….

(ii) …………………………………………

examples ………………………………… and …………………………………

(iii) ……………………………………………

examples …………………………………. and ………………………………….

(c) The problem facing Tanzania society is misuses of charcoal and fire wood as a

source of fuel. Give two points of advice to the society on how to use less

charcoal and firewood efficiently.

3. (a) Write P for primary and S for secondary in the following fuels.

Wood……………. Petrol…………… Coal gas……………………….

(b) Which gaseous fuels are a result of the following processes?

(i) Destructive distillation of coal…………………………………….

(ii) Destructive distillation of wood…………………………..........

(iii)Air reacts with red hot coke at 1000⁰C……………………..

4. (a) Write the chemical symbol for each of the following elements.

1. Argon_________(ii)Lead________(iii)Silver__________(iv)Manganese____ (v) Barium______________(vi)Xenon_____________.

(b) Write the chemical formulae of the following compounds:-

1. Potassium sulphate

2. Copper (II) carbonate

3. Aluminium oxide

4. Magnesium hydroxide

5. Explain the major ways of obtaining artificial fuels from natural fuels in all the three states of matter.

6. By the help of a well labeled diagram explain how one can conduct an experiment on destructive distillation of coal.

7. (a) What is fuel

(b)Give two example of each of following categories of fuels

1. Solid fuel

2. Liquid fuel

3. Gaseous fuel

( c) State any two qualities of good fuel

8. (a) Define the following terms

1. Green house effect

2. Global warming

3. Acidic rains

4. Pollution

(b)Give any four examples of green house gases

9. (a) Define the following terms:

   1. Fuel ……………………………………………………………………………………………………………………………………………………

   2. Calorific value of a fuel ……………………………………………………………………………………………………………………………………………………

   3. Energy value of a fuel ……………………………………………………………………………………………………………………………………………………

(b) Give two examples of each of the following:

(i) Solid fuel ………………………………….., ……………………………..

(ii) Liquid fuel…………………………………..,……………………………...

(iii) Gaseous fuel ……………………………….., …………………………….

(c) Name four characteristics of a good fuel

(i) ………………………………………………………………………………

(ii) ………………………………………………………………………………

(iii) ……………………………………………………………………………..

(iv) ……………………………………………………………………………..

LEARNING HUB.TZ

CHEMISTRY EXAMINATION FORM TWO

TOPICAL EXAMINATIONS.

ATOMIC STRUCTURE

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, and B

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

1. SECTION A 20 MARKS

1. What is so unique about a hydrogen atom on comparing it with other elements?

1. It has no neutron in its nucleus

2. It has a small relative atomic mass

3. It forms a low density gas

4. It has no exact place in the Periodic table

2. What is so special with Francium and Fluorine compared to other elements in the periodic table?

1. Francium is a liquid and Fluorine is a gas

2. Francium is in group 1 and Fluorine in group 7

3. Francium is in periodic 7 and Fluorine in period 2

4. Francium is most electropositive and Fluorine most electronegative.

3. Which of the following group of gases are monoatomic at room temperature?

1. Noble gases

2. Gases of group 6 and 7

3. Ammonia and nitrogen

4. Hydrogen and phosphine

4. An atom T has 12 electrons and atom Z has 17 electrons. When the two atoms react to form a compound the formula of the resulting compound will be:-

1. TZ₂ B. T₂Z C. T₂Z₃ D. T₃Z₂

4. An element T with electronic configuration 2: 8: 3 belongs to group ……………... and period …………………

1. 111 and 3

2. 11 and 3

3. 111 and 2

4. 11 and 2

4. Give an arbitrary ₁₆X: its electronic configuration is ………………………

1. 2: 8: 3

2. 2: 8: 4

3. 2: 8: 6

4. 2: 10: 4

4. Hydrogen is placed in group 1 elements because ……………………..

1. It is a metal

2. It loses electron to form compounds

3. It is an inert gas

4. Its atomic number is 1

4. What are nucleons?

1. Neutrons

2. Neutrons and protons

3. Electrons

4. Protons, Neutrons and electrons

4. Most atoms are neutral because. ……………

1. the nucleus is only made up of neutrons

2. there are equal number of electrons and protons in the shells

3. the neutrons normally have zero charge.

4. the number of electrons balances out the number of protons in the atom.

4. The maximum number of electronic in the innermost shell of an atom is ………………

1. 3 B. 1 C. 4 D. 2

4. What is the mass of an electron compared to that of a proton?

1. ¹/₁₈ B. ¹/₁₈₄ C. ¹/₁₈₄₀ D. ¹/₁₈₄₀₀

2. Match the items of COLUMN A to the statements of COLUMN B to make a meaningful scientific idea or statement.

Write the letter of the best match from column B against a statement in column A

SECTION B

3. (a) Which are the three sub – atomic particles;

1. ……………………………. (ii) …………………………….. (iii) ……………………............

(b) Which sub – atomic particles from the nucleus and what is their common name?

Particles (i) ……………………………. (ii) …………………………………………

Common name …………………………………………………….

3. (a) Write the electronic configuration of the following elements;

₁₁Na: …………………………………………………………

₂₀Ca: …………………………………………………………

₁₇CC: ………………………………………………………..

(b) Derive the periods and groups of the above elements from their electronic configurations;

Element	Group	Period
Na
Ca
Cl

3. Atoms of the same element are identical (=all alike in properties have same mass and size);

1. Name the person who developed the above theory; …………………………………………………………………………………………………

2. Did this theory face any challenge? Explain ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..

3. How can you derive a molecule formula from an empirical formula. A certain compound contains 22.7% zinc, 11.0% sulphur, 22.3% oxygen and the rest water of crystallization. Derive the systematic name of the chemical formula of the compound if its relative atomic mass, Ar is 287. (zn = 65, O = 16, H = 1, S = 32).

4. (a) Calculate relative atomic mass of Boron Ar_B if the percentage relative abundances of its isotopes are

as follows;

B – 10 is 75% and B = 11 is 25% ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

(b) Calculate the formula mass of the following compounds;

Na₂CO₃, HCl and H₂SO₄

[S = 32, H = 1, C = 12, Na = 23, O = 16, Cl = 35.5] …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

3. An atom of an element is represented as _{ }

1. What does the numeral 23 indicate? ………………………………………………………….

2. What does the numeral 11 indicate? …………………………………………………………..

3. What is the number of protons in X? ………………………………………………………….

4. What is the number of elections in X? ……………………………………………………….

5. What is he number of neutrons in X? …………………………………………………………

3. (a) Isotopes of oxygen , and and abundances 99.760%, 0.030% and 0.202%.

Find R.A.M.

2. Define the following terms;

1. An atom …………………………………………………………………………………………………………………………………………………………………………………………

2. An element …………………………………………………………………………………………………………………………………………………………………………………………

3. Isotopy …………………………………………………………………………………………………………………………………………………………………………………………

4. Atomic number …………………………………………………………………………………………………………………………………………………………………………………………

5. Electronic configuration …………………………………………………………………………………………………………………………………………………………………………………………

3. (a) Give the IUPAC names for each of the following compounds:-

1. Cu₂O______________________(ii)Na₂SO_{4_________________________________}

2. Fe₂O₃__________________________

(b) Calculate the oxidation number of underlined elements:-

(i) CO^2- (ii) HCO₃ (iii) KClO₃

(c) Write the electronic configuration of Cl^- and hence draw its electronic diagram^.

3. (a) Define:

   1. Empirical formula ……………………………………………………………………………………………………………………………………………………

   2. Molecular formula ……………………………………………………………………………………………………………………………………………………

(b) A certain gaseous compound contains 82.8% of carbon and 17.2% of hydrogen by mass. The vapour density of the compound is 29. Calculate its molecular formula (C = 12, H = 1)

LEARNING HUB.TZ

CHEMISTRY EXAMINATION FORM TWO

TOPICAL EXAMINATIONS.

PERIODIC CLASSIFICATIONS

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, and B

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

1. SECTION A 20 MARKS

1. What is so special with Francium and Fluorine compared to other elements in the periodic table?

1. Francium is a liquid and Fluorine is a gas

2. Francium is in group 1 and Fluorine in group 7

3. Francium is in periodic 7 and Fluorine in period 2

   1. Francium is most electropositive and Fluorine most electronegative.

1. Which of the following group of gases are monoatomic at room temperature?

1. Noble gases

2. Gases of group 6 and 7

3. Ammonia and nitrogen

4. Hydrogen and phosphine

2. Where can one place an element ₉X in the periodic table?

1. Periodic 2 group VII

2. Periodic 7 group II

3. Periodic 8 group O

4. Periodic 9 group II

3. The modern Periodic Table is as the result and study of;

1. John Newland

2. Dmitri Mendeleev

3. Isaac Newton

4. John Dalton

4. An element T with electronic configuration 2: 8: 3 belongs to group ……………... and period …………………

1. 111 and 3

2. 11 and 3

3. 111 and 2

4. 11 and 2

5. When element T of Group 1 combines with element X of Group VI, the formula of the compound formed is;

1. T₂X B. X₂T C. TX₂ D. XT₄

2.Match the items of COLUMN A to the statements of COLUMN B to make a meaningful scientific idea or statement.

COLUMN A

COLUMN B

Early classification of elements. Alkali metals. Dobereiner classification. Halogens Newlands clarification. D.L Mendeleev’s classification. Alkaline earth metals. Noble gases Niel Bohr’s work. H.J. Mosely’s work

Use of physical and chemical properties metals and non metals to arrange elements. Group elements showing typical properties of metals and non – metals. Strongly metallic (=electropositive) elements reacting with water to form alkaline solutions. Formation of non – metal ions or radicals of similar charge to metal ions. Transition elements in between group II and group III have properties in between those groups. Arrangement of elements in triads in order of increasing atomic weight such that the middle element is average weight of the other two. Salt maker and most electronegative elements. Derivation of molecular formulae from empirical formulae. The group number under which the element falls indicates valence shell electrons. On arranging elements in order of increasing atomic weight, the 8th element is placed under the first one due to similar chemical properties. Block elements have their last electrons according to subshell’s belonging to the subshell’s. On arranging elements in order of increasing atomic weight to seven columns, those of similar properties form regular intervals called periodicity. Elements of similar chemical properties but less reactive than group one elements. The most reactive metal in the P.T. is Francium while the most reactive. non – metal is Fluorine. Not all electrons are paired when electronic formulae of elements are written. Rare, inert and monoatomic free elements with stable electron structures of their outermost shells. Arranging elements in groups and in periods on the basis of electronic configuration makes the long form of the periodic table of elements. Old names and trivial names are left out except those accepted by the modern system of nomenclature. Electronegativity and electron affinity are associated with non – metallic elements while Electropositivity is associated with metallic elements. Systematic arrangement of elements in order of increasing atomic numbers results into groups and periods showing similarities in properties.

3. (a) What is ionization energy ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

(b) How does ionization energy change down the group elements and across them (from left to right) in

the periodic table; …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

3. (a) What is the difference in melting points and in Boiling points between the elements of group IV and

group I or group VII elements? …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

(b) Which is the common property carried by the following element B, Si, Ge, As, Sb, Te and Po? Give

one reason to your answer?

Property …………………………………………………………………………………………………………………………………………………………………………………………………………………………

Reason …………………………………………………………………………………………………………………………………………………………………………………………………………………………

3. An element Y has an atomic number of 16 and mass number of 34. State the composition of the Y^2- ion in terms of the number of protons, electrons and neutrons.

4. Explain why the latent heats of fusion and vapourasization increase from sodium to aluminum in the third period of the periodic of the periodic table.

5. The following are atomic and ionic radii (in nm) of members of the same group of the periodic table.use the information to answer the questions that follow. The letters do not represent the actual

Element	Atomic radii (nm)	Ionic (nm)
A B C D E	0.157 0.216 0.133 0.235 0.203	0.098 0.149 0.078 0.165 0.133

1. Is this a group of metallic or non metallic elements? Explain your answer?

2. State the element that would have lowest atomic number.

3. State the element which would be the most reactive. Give a reason for your answer.

4. State the element which would be the most reactive. Give a reason for your answer.

5. M,N and Z represent elements in the same period of the periodic table. The oxides of the elents are MO_2, NO and ZO₃ respectably. Using the letters, M, N and Z to represent the elements answer the following questions.

1. Write down the elements in the order in which they appear in the periodic table. Justify your answer.

2. State the element that would have the lowest atomic number.

3. State the element that you would be the best conductor of electricity. Explain your answer.

3. Study the following given the table below and answer the questions that follow. The letters do not represent the actual symbols of the elements.

element	Atomic number	Boiling point (K)
S T U V W	3 13 16 18 19	1603 2743 718 87 1047

1. Select the elements which belong to the same period.

2. Giving reasons in each case, select an element which:

1. Is un gaseous state at room temperature.

2. Is in gaseous state at room temperature.

3. Does not form an oxide

3. Write down the formulae of the following.

1. The nitrate of T.

2. The compound formed of the following U and S.

3. Name the type of bond that exists in the compound formed when elements U and W React. Give a reason for your answer.

3. Using the information tabulated below, answer the questions that follow. The letters do not represent the actual symbols of the elements.

oxide	J O	TO	X O	W O	Y O	ZO
Ph of oxides in water	13	9	X	X	1	4
Melting point (	1193	3075	2045	1728	563	-91

1. Identify the oxide with a :

• Giant atomic structure

• Giant atomic structure

• Simple molecular structure

2. Explain the trends in the melting points of the oxides.

3. Write down the formula of the chloride of W.

4. Explain why WO₂ is solid while carbon (IV) oxide (CO₂) is a gas at room temperature, yet W and carbon are in the same group.

5. Using the dots (.) and cross (x) ,draw the structure of the following compounds.

1. Chloride T

2. Chloride of W

3. An element Y has atomic number 16 and mass number 34. Describe the composition of y ion in terms of the number of protons, electrons and neutrons present.

4. Elements P and Q were burnt in the air and the oxides collected and dissolved in water. P has electronic configuration 2.8.8.2, while Q has electronic configuration 2.8.5 describe the nature of the two oxides.

3. Elements A, B, C and D have atom number 6, 8,17 and 20 respectively.

   1. Write the electronic structures of A, B, C ,and D

   2. What are the normal Valences of these elements

   3. Write down the formulae of the simplest compounds you would expect when:

1. A chemically combines with B

2. A chemically combines with C

3. C chemically combines with D

4. D chemically combines with B

4. Mention the types of bonding you would expect to occur in each of the above compounds.

5. List three differences in properties you would except to find between the compounds as a result of their differences in type of boiling

LEARNING HUB.TZ

CHEMISTRY EXAMINATION FORM TWO

TOPICAL EXAMINATIONS.

BONDING AND NOMENCLATURE

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, and B

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

1. SECTION A 20 MARKS

1. What would be the correct chemical formula out of the name Lead (II) trioxonitrate (V)?

1. Pb (NO₂)₂ B. Pb(NO₂)₄ C. Pb (NO₃)₄ D. Pb (NO₃)₂

2. When electrons are transferred completely from a metallic atom to a non – metallic one, what is the name of bond which is formed by the combining atoms?

1. Hydrogen bond

2. Covalent bond

3. Ionic bond

4. Dative covalent bond

3. Which of the following group of atoms will form heteropolar covalent bonds after they have combined to one another?

1. Oxygen atoms

2. Chlorine atoms

3. Hydrogen and chlorine

4. Hydrogen and carbon

4. How many unbounded (=lone) pairs of electron are there in the water molecule as shown in its structural formula;

1. 1 B. 2 C. 3 D. 4

5. Which element frequently combines differently with non – metallic elements and causes different oxidation states of the non – metallic elements other than hydrogen?

1. Sulphur B. Chlorine C. Carbon D. Oxygen

6. Which of the following chemical species have the same number of electrons?

1. Cl, Be and O^2-

2. K+, Ca²+, Cl^- and Mg²⁺

3. O^2-, Ca²⁺ and Mg²⁺ ( )

4. Na⁺, Mg^2+, Be²⁺ and Li.

7. The following group of elements have a valence of one each

1. Li, Na and K

2. Be, Mg and Ca

3. C, Si and Ti

4. Li, Si and Ti

8. How many groups and periods are there in the modern periodic table respectively?

1. VI and 7

2. VII and 8

3. VI and 8

4. VIII and 7

9. Which two elements are likely to form the strongest electrovalent bond?

1. Calcium and phosphorous

2. Sodium and chlorine

3. Hydrogen and oxygen

4. Carbon and aluminium

10. Which element will form a compound of the formular M2O3 where M is a metal?

1. Aluminium and Oxygen

2. Beryllium and chlorine

3. Oxygen and Sodium

4. Calcium and oxygen.

2. Match the following items by writing the letter of the best match against a number in the table below;

COLUMN A

COLUMN B

The number of hydrogen atoms which can combine with an element. Sulphur dioxide, SO2 Agrees with the relative molecular mass of the compound. % mass composition ÷ relative atomic mass Oxidation state of non metallic element other than oxygen is 5. Electronic formula diagram related to a covalent bond. Radical Chemical formula of tetraoxosulphate (VII) acid. Dative covalency Do not produce ions in their normal state.

AL2SO4 H2SO3 Property of ionic compounds and polar molecules. Property of covalent compounds X Y [X]+ [ Y ] Valency Oxidation state Na2SO4 KClO3 Shared electron pair is a result of each combining atom contributing an electron. Shared electron pair comes from one of the combining atoms. H2SO4 SO A binary compound. Triatomic gas Moles reacting Simple ratio of moles Molecular formula Empirical formula

2. (a) Find out the oxidation states of the underlined elements in the following compounds;

HClO₃ ……………………………………………………………………………………….

HNO₃ ………………………………………………………………………………………

CuSO₄ ………………………………………………………………………………………

(b) What is the difference between oxidation number and the valency of an element ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

2. (a) Write systematic names of the following compounds bearing common names.

Sulphuric acid ……………………………………………………………………………………….

Nitric acid ……………………………………………………………………………………………

Hydrochloric acid …………………………………………………………………………………….

(b) What are the chemical formulae of the above named compounds …………………………………………………………………………………………………………………………………………………………………………………………………………………………

2. (a) write down the chemical formula of the following compounds

1. Copper (II) nitrate _____________________________

2. Sodium hydrogen carbonate _________________________

3. Aluminium chloride _______________________________

(b) Write the IUPAC names of the following chemical compounds:

(i) H₂SO₄ ________________________________________________

(ii) HCl O₃ __________________________________________________

(iii) Cu₂O ____________________________________________________

2. (a) Calculate the oxidation number of

1. S in Na₂SO₄

2. N in NO₂^-

3. Pb in Pb (NO₃)₂

(b) What do you understand by the terms chemical kinetics and energetic?

2. By way of electronic formula of hydrogen atom and oxygen atom, show how the two elements are bonded in water molecule.

3. (a) Define:- (i) Valency (ii) oxidation state (iii) Radical.

(b) Calculate the oxidation number of the underlined elements:-

(i) Na₂SO₄ (ii) SO₄^2- (iii) K₂Cr₂O₇ (iv) NH₄⁺ (v) MnO₄^-

(c ) Give the systematic ( I.U.P.A.C) names of the following compounds:-

2. Na₂CO₃ (II) AlCl₃ (III) CuO.

3. (a) Group the following compounds as ionic, (l) and covalent, (C) by writing the

bracketed letter infront of the compounds;

NaCl ( ) HCl ( ) MgO ( )

H₂O ( ) SO₂ ( ) MgCl₂ ( )

(b) Give two reasons for which NaCl has a stronger bond than MgCl₂;

Reasons (i) …………………………………………………………………………

(ii) ………………………………………………………………………….

2. (a) Define hetevopolar covalent bonds and homopolar covalent bonds;

Heteroplar covalent bond ……………………………………………………………………………………………………………………………………………………………………………………………...

Homopolar covalent bond …………………………………………………………………………………………………………………………………………………………………………………………….

(b) Group the following molecules as heteropolar or homopolar;

O₂, HCl, Cl₂, H₂O, H₂S, H₂

Heteropolar ………………………………………………………………………....................................................................................................................................................................................

Homopolar ………………………………………………………………………………………………………………………………………………………………………………………………

2. Show covalent bond formation in CO₂ molecule and in MgCl₂ by way of both electronic structure diagram and electronic formulae.

Molecule	Electronic structure diagram	Electronic formula
CO2
MgCl2

2. Find out the oxidation states of the underlined elements in the following chemical compounds shown by their chemical formulae and then derive their systematic chemical names;

Chemical formulae	Oxidation state	Systematic chemical name
Na2SO4.10H2O
HNO3
HPO42-

2. (a) What is the suitable term in chemistry used for the tendency of an atom to attract an

electron pair towards itself? …………………………………………………………

(b) Can isolated atoms show the same behaviour? …………………………………….

(c) Which is the suitable term in chemistry used in opposite to the 7(a) and 7(b)

behaviours above? …………………………………………………………………

………………………………………………………………………………………

2. Explain why hydrogen gas is produced when magnesium is added to hydrogen chloride in water , but no hydrogen gas is produced when magnesium is added to a solution of hydrogen in methyl benzene.