THE UNITED REPUBLIC OF TANZANIA MINISTRY OF EDUCATION AND VOCATIONAL TRAINING

FORM TWO SECONDARY EDUCATION EXAMINATION, 2004

0032 CHEMISTRY

TIME: 2 HOURS

INSTRUCTIONS

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

2. Answer all questions in spaces provided for each question.

3. Write your examination number on the top right hand corner of every page.

4. All writing must be done in “black or blue pen” except for the diagrams which must be in pencil.

5. Cellphones and calculators are not allowed in the examination room.

6. The following constants may be used:

Atomic masses: H = 1, C = 12, O = 16, and Na = 23.

SECTION A

1. Write down the letter of the most correct response for each of the following questions:

(i) Which of the following reactions represent chemical change?

1. Heating a solid ammonium chloride in a test tube;
2. Burning candle in air;
3. Adding sodium chloride solid in water;
4. Putting ink on a filter paper.

(ii) Which of the following sets of symbols of elements stand for a single element?

(iii) An element 'A' of electronic configuration 2:8:3 combines with an element 'B' of configuration 2:6.

The chemical formula of the compound is: 

1. B₆A₃
2. A₃B₃
3. A₂B₃
4. A₃B₂

(iv) Calcium iron and calcium atom both have:

1. Same physical properties
2. Same number of protons
3. Same number of electrons
4. Same electronic configuration

(v) If a Bunsen burner flame produces much soot, which is the correct conclusion?

1. The air hole is closed
2. The burner gas jet is big
3. The air hole is fully opened
4. The gas supply is poor

(vi) The atomic number of an element is the:

1. Number of protons and neutrons
2. Number of neutrons
3. Mass number
4. Number of protons

(vii) If water does not easily form lather with soap, it is because of the presence of:

1. Calcium and magnesium salts
2. Calcium sulphate
3. Sodium and calcium salts
4. Ammonium and Magnesium salts

(viii)This mixture of substance can extinguish fire:

1. Oxygen and Nitrogen
2. Carbon dioxide and sand
3. Carbon dioxide and Hydrogen
4. Hydrogen and Neon

(ix) Which of the following sets of processes represent uses of oxygen gas?

1. Welding, ice melting, magnetization
2. Mountaineering, sublimation, freezing
3. Glass cutting, desiccation, welding
4. Diving, welding, mountaineering

(x) The reaction that takes place when NaHC03 is heated in the laboratory can be described as: 

1. Combination
2. Decomposition
3. Replacement
4. Double decomposition

SECTION B

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

SECTION C

3.(a) (i) What is air?

(ii) Write down four constituents of air.

(b) Water is said to be a compound. Verify this statement. 

(c) Distinguish between solution and suspension.

4. (a) Mention any three laboratory rules.

(b) Name any three places or areas where the knowledge of Chemistry is applied.

(c) State what is observed when the following simple experiments are performed:

(i) Blue litmus paper is dipped into dilute hydrochloric acid.

(ii) A piece of white paper is placed into a non-luminous flame. 

(iii) A glowing splint is lowered into a jar full of oxygen.

5. (a) Define a chemical equation.

(b)Complete and balance the following chemical equations:

(i) MgO + HCI →   . . . . . . + H₂O

(ii) Ca(OH)₂ H₂SO₄  →  . . . . . . .+ H₂O

(iii) KClO₃ →  KCl + . . . . . . 

(iv) H + H₂O →  . . . . . .

6. (a) Use the IUPAC system to name the following chemical compounds:

(i) Cuo 

(ii) CaSO₄

(iii) HNO₃ 

(iv) ZnCl₂

(b) Write a balanced Ionic chemical equation for the following reactions:

(i)

(ii)

(c) Write the symbols for the following elements:

(i) Silver 

(ii) Copper

(iii) Iron 

(iv) Mercury

(d) Draw an electronic configuration to illustrate the structure of atoms P and Q with 13 and 17 protons.

(e) From the structures drawn in (d) above state the valency, period and group where the atoms are placed in the Periodic Table.

7. (a) What is the meaning of covalent bonding?

(b) Mention four differences between covalent and electrovalent compounds.

8. Define the empirical formula.

(b) A compound M is composed of 52.2% carbon, 13% hydrogen and the rest is oxygen. If the molecular mass of M is 138, calculate: 

(i) The empirical formula

(ii) The molecular formula