THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATIONS COUNCIL

FORM TWO SECONDARY EDUCATION EXAMINATION

032 CHEMISTRY

Time: 2:30 Hours  Thursday, 19^th November 2015 a.m.  

Instructions

1. This paper consists of sections A, B and C.
2. Answer all questions in the spaces provided.
3. All writing must be in black or blue ink except diagrams which must be in pencil.
4. All communication devices and calculators are not allowed in the examination room.
5. Write your Examination Number at the top right corner of every page.
6. The following atomic masses may be used: H = 1, O = 16, C = 12, N = 14, Na = 23, Al = 27, S = 32, K = 39, Ca = 40, Fe = 56, F = 19, Cu = 64.

SECTION A (10 Marks)

1. For each of the items (i) – (x), choose the correct answer from the given alternatives and write its letter in the box provided.

(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. anion
3. cation
4. 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. ¹⁵₇X, ¹⁶₇X, ¹⁹₇X
2. ¹⁷₈X, ¹⁸₈X, ¹⁸₆X
3. ¹⁶₈X, ¹⁷₈X, ¹⁸₉X
4. ¹⁶₈X, ¹⁷₈X, ¹⁸₈X

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

1. Cobalt II oxide
2. Cobalt III oxide
3. Cobalt chloride
4. Copper II chloride.

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

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.

SECTION B (20 Marks)

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.

SECTION C (70 Marks)

3.

(a) Define the following terms:

1. Oxidation state
2. An element
3. A compound
4. Faintin

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

1. Sodium sulphate 
2. Sodium chloride
3. Calcium nitrate
4. 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 'X'.

(c) Mention three chemical properties of gas 'X'.

(d) State three uses of gas 'X'.

5.

(a) Write the name of each of the following compounds:

1. (NH₄)₂CO₃
2. CaCl₂ 
3. Na₂SO₄ 
4. KClO₃ 

(b) Give three differences between the following:

(i) Electrovalent compounds and covalent compounds.

(ii) Solutions and suspensions.

6.

(a) State two chemical properties of water.

(b) Calculate the molar mass of each of the following compounds:

1. Al₂(SO₄)₃
2. NaHCO₃
3. Fe₂O₃

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

1. Burning of charcoal
2. Rusting of iron sheets

7.

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

(i) Write the collective name of elements in:

Group II 

Group VIII

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

A, B, C, D

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

E,F,G,H

(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?

1. Thistle funnel
2. Pipette
3. Wire gauze
4. 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.

(c) State two uses of gas Z.

10.

(a) Define the following terms:

1. Empirical formula
2. 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.