THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATIONS COUNCIL

CERTIFICATE OF SECONDARY EDUCATION EXAMINATION 

032/1  CHEMISTRY 1

 (For Both School and Private Candidates)

Time: 3 Hours  Thursday, 06^th November 2014 p.m.

 Instructions

1. This paper consists of sections A, B and C.
2. Answer all questions in this paper.
3.  Calculators and cellular phones are not allowed in the examination room.
4.  Write your Examination Number on every page of your answer booklet(s).
5.  The following constants may be used.

 Atomic masses:

 H = 1, C = 12, N = 14, Na = 23, S = 32, O = 16, Al = 26, Cl = 35.5 Ca = 40, Mn = 55, Fe = 56, K = 39.

 Avogadro’s number = 6.02 x 10²³.

 GMV at s.t.p. = 22.4 dm³.

 1 faraday = 96,500 coulombs.

 Standard pressure = 760 mm Hg.

 Standard temperature = 273 K.

 1 litre = 1 dm³ = 1000 cm³.

SECTION A (20 Marks)

Answer all questions in this section.

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

(i)  An element in the periodic table with atomic number 18 belongs to which of the following?

1. Group I and period I.
2. Group O and period III.
3. Group III and period III.
4. Group V and period IV.
5. Group VII and period IV.

(ii)  The ionic equation when aqueous ammonium chloride reacts with sodium hydroxide solution is represented as:

1. 2NH+4(aq) + 2Cl-(aq)à 2NH3(g) + Cl2(g) + H2(g)
2. NH+4(aq) + OH-(aq) à NH3(g) + H2O(l)
3. Na+(aq) + Cl-(aq) à NaCl(g)
4. H+(aq) + OH-(aq) à H2O(l)
5. 2NH+4(aq) + 2Cl-(aq) à 2NH3(g) + 2HCl(g).

(iii)  The reason why white anhydrous copper (II) sulphate turns blue when exposed in atmosphere is that it,

1.   reacts with carbon dioxide.
2. reacts with oxygen
3. becomes dry.
4. absorbs water vapour.
5. decomposes.

 (iv)  Chemical change means;

1.   the change is reversible.
2. can easily be separated.
3. the change is complete.
4. new substance is produced.
5. produces no change of mass.

(v)  If a stead current of 2 amperes was passed through an aqueous solution of iron (II) sulphate for 15 minutes, then the mass of iron deposited at the cathode will be:

1. 54 g.
2. 56 g.
3. 0.54 g.
4. 28 g.
5. 0.52 g.

(vi)  10 cm³ of 0.4 M sodium hydroxide are added to 40 cm³ of 0.2 M hydrochloric acid. The resulting mixture will be

1. Neutral
2. Alkaline
3. Dilute
4. Acidic
5. Amphoteric

(vii)  The only metal which does not react with dilute hydrochloric acid is

1. Magnesium
2. Aluminum
3. Copper
4. Zinc
5. Sodium.

(viii)  Which of the following solutions is the most concentrated?

1. 50 g of calcium carbonate in 100 cm³ of water
2. 60 g of sodium chloride in 200 cm³ of water
3. 65 g of potassium nitrate in 100 cm³ of water
4. 120 g of potassium sulphate in 200 cm³ of water
5. 50 g of sodium hydroxide in 200 cm³ of water.

ix) Alcohols react with carboxylic acids to form a group of organic compounds called

1. alkynes
2. aldehydes
3. ethers
4. esters
5. alkanols.

(x) Which of the following statement is true about water gas?

1. It is poisonous.
2. Contains hydrogen.
3. Is the same as biogas.
4. Contains hydrogen and nitrogen.
5. Contains carbon monoxide and hydrogen.