THE UNITED REPUBLIC OF TANZANIA MINISTRY OF EDUCATION AND VOCATIONAL TRAINING

FORM TWO SECONDARY EDUCATION EXAMINATION, 2008

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 corresponding to the most correct answer for each question.

(i) Separation of a mixture by fractional distillation is possible if the mixture constituents differ in their:

1. Boiling points
2. Melting points
3. Vapourizing points
4. Freezing points

(ii) The valency of an element with atomic number 10 is:

1. 2
2. 3
3. 0
4. 1

(iii) When element T of Group I combines with element X of Group VI, the formula of the compound formed is:

1. T₂X 
2. X₂T
3. TX₂
4. XT₄

(iv) A metal atom can become an ion by electron:

1. Attraction 
2. Gain
3. Loss 
4. Sharing

(v) How many protons, neutrons and electrons are there in an atom represented by the symbol ³⁹₁₉K?

(vi) Which of the following warning signs is likely to appear on the bottle containing concentrated nitric acid in the laboratory? 

1. Corrosive
2. Explosive
3. Flammable
4. Irritant

(vii) Saturated solution is one which:

1. Contains more solute undissolved at a given temperature.
2. Will take no more of solute at a given temperature.
3. Contains a little solute at a given temperature.
4. Has a large amount of solvent at a given temperature.

(viii)The percentage of C in C₂H₆ is:

1. 20 
2. 40
3. 60
4. 80

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

1. 2:8:8:1 and 2:8:8:7
2. 2:8:3 and 2:8
3. 2:8:8:1 and 2:8:3
4. 2:8:6 and 2:8:8:7

(x) Hard water which can be softened by boiling method contains dissolved:

1. calcium carbonate 
2. calcium sulphate
3. magnesium chloride 
4. magnesium hydrogen carbonate

SECTION B

2. Choose a word(s) from list B which matches the statement or phrase in list A and write its letter against the appropriate question item.

SECTION C

3. (a) By giving one example, define the following terms:

(i) Suspension

(ii) Chromatography

(b) Briefly explain the following ways of preventing rusting:

(i) Electroplating

(ii) Galvanizing

4. (a) Define the term "Element".

(b) Write a symbol for each of the following elements:

(i) Potassium

(ii) Copper

(iii) Lead

(iv) Neon

(c) Write the formulae of the following compounds:

(i) Sodium chloride

(ii) Aluminium oxide

(iii) Water

(iv) Iron(III)sulphate

5. (a) Define:

(i) Empirical formula

(ii) Molecular formula

(b) A certain compound contains 22.7% of Zinc, 11.0% of Sulphur, 22.3% of Oxygen and the rest being water of crystallization. Calculate:

(i) Empirical formula

(ii) Molecular formula of a compound if its molar mass is 287gm.

6. (a) What is matter?

(b) Write the names of the following processes of changing matter from one state to another:

(i) Solid to liquid

(ii) Liquid to gas

(iii) Gas to liquid

(iv) Liquid to solid

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

(i) FeCl₂

(ii) CuSO₄

(iii) H₂SO₄

(iv) CO₂

7. Study the Periodic Table below:

Use the letters shown in the Periodic Table above to indicate:

(i) Elements with zero valency

(ii) The lightest atom

(iii) The alkaline earth metal

(iv) An element with electronic configuration of 2:8:1

(v) Give the names of elements represented by the mentioned letters A, B, C and D.

(vi) Give the name of J as an element.

(vii) Write the electronic configuration of J.

8. (a) Give the systematic (IUPAC) names for the following compounds:

(i)N₂O₃

(ii) NH₃

(iii)H₂SO₄

(iv) CuO

(b) (i) What do you understand by the term Isotope?

(ii) If sample X consists of 99.76% of ¹⁶X; 0.04% of ¹⁷X and 0.2% of ¹⁸X, calculate the relative atomic mass of X.

(c) Write the formulae of the following compounds:

(i) Hydrogen chloride

(ii) Magnesium carbonate

(iii) Sodium carbonate

(iv) Magnesium sulphate

9. (a) What is the importance of the indicators in a chemical reaction?

(b) What colour change will be formed when a blue litmus paper is placed in the test tube containing:

(i) Nitrogen dioxide gas?

(ii) Water?

(iii) Calcium hydroxide?

(iv) Hydrogen chloride gas?

(c) Give a reason for each of the following observations:

(i) Mercury does not displace hydrogen from acids.

(ii) Luminous flame is not commonly used in the laboratory for heating.

(iii) The mixture of sand and potassium iodide can be separated by heating.

(iv) Covalent compounds are not good conductors of heat and electricity.

10.(a) Using a large and well labelled diagram show the laboratory preparation of hydrogen from zinc granules and dilute sulphuric acid.

(b) Write a balanced chemical equation for the chemical reaction taking place in (a) above.

(c) Give four uses of hydrogen gas.