THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATIONS COUNCIL OF TANZANIA
CERTIFICATE OF SECONDARY EDUCATION EXAMINATION
032/1 CHEMISTRY 1
(For Both School and Private Candidates)
Time: 3 Hours Thursday, 07th November 2019 a.m.
Instructions
Atomic masses: H 1, O- 16, N- 14, S = 32, Zn - 65, Cl -35.5, cu - 64.
Avogadros 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 cm 3.
SECTION A (15 Marks)
Answer all questions in this section.
1. For each of the items (i) — (x), choose the correct answer from among the given alternatives and write its letter beside the item number in the answer booklet provided.
(i) "Water is referred to as the universal solvent". What does this mean?
(ii) When methane undergoes substitutional reaction with excess chlorine, what is the final product?
(iii) Why is hydrogen gas collected over water and by upward delivery method?
(iv) Consider the following fuels which are used for different purposes:
Which fuels originate from fossils?
(v) The following are the uses of chromatography except:
(vi) What is the proper set of apparatus would you use to grind granules of a solid substance into fine powder in the laboratory?
(vii) Oxygen gas can be produced in a large scale by:
(viii) Which of the following sets of processes uses a gas that ignites with a "pop" sound when a lighted splint is passed through it?
(ix) Which statement is the most correct about chemistry laboratory?
(x) Which role does the organic matter play in the soil?
2. Match the descriptions in List A with the corresponding scientific procedures in List B by writing the letter of the correct response besides the item number in the answer booklet provided.
LIST 1 | LIST B |
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SECTION B (70 Marks)
Answer all questions in this section.
3. (a) How many chlorine molecules are in 20 cm of chlorine gas at s.t.p?
(b)Calculate the number of ions present in 5 g of copper II nitrate. (7 marks)
View Ans4. (a) Distinguish normal salts from acidic salts based on how they are formed.
View Ans(b) Give four uses of salts in daily life. (7 marks)
View Ans5. (a) Distinguish temporary hardness from permanent hardness of water.
View Ans(b) With the help of chemical equations, explain how you can remove each type of water hardness in 5(a). (7 marks)
View Ans6. In the industrial preparation of sulphur trioxide, equilibrium is established between sulphur dioxide and oxygen gas as follows:
(a)(i) Is the forward reaction an endothermic or exothermic process? Give a reason.
View Ans(ii) How would you adjust temperature and pressure to maximize the proportion of the product at equilibrium?
View Ans(b) (i) Why is it unfavorable to work with very high pressure and very low temperature in the Contact process?
View Ans(ii) What catalyst is used to speed up the rate of formation of sulphur trioxide before attaining the equilibrium? (7 marks)
View Ans7. An atom of element X having atomic number 11 combines with an atom of element Y haying atomic number 9 to form a compound.
(a) Write the formula of the compound and state the type of bond formed in the compound.
View Ans(b) Give four properties of the compound formed in 7(a). (7 marks)
View Ans8. Explain each of the following statements and in each give its balanced chemical equation:
9. (a) Write the chemical symbols for beryllium, boron, neon, nitrogen and phosphorus.
View Ans(b) Why some of the elements in 9(a) are assigned symbols with only one letter while others bear symbols with two letters? (7 marks)
View Ans10.(a) Give three advantages of using chemical equations over word equations.
View Ans(b) You are provided with a compound composed of 22.2% zinc, 11.6% sulphur, 22.3% oxygen, and the rest percentage is water of crystallization. Calculate the molecular formula of the compound if its molecular mass is 283. (7 marks)
View Ans11 . A Form Three student conducted experiments in the laboratory to synthesize nitrogen, ammonia and ethane. The experimental results were tabulated as follows:
Experiment | | Conditions | Products |
1 | Lead nitrate | Heat | Lead oxide, oxygen gas and nitrogen gas |
2 | Gaseous hydrogen and gaseous nitrogen | Catalyst | Ammonia gas |
3 | Ethene gas and hydrogen gas | Catalyst | Ethane |
Write word equations with corresponding chemical equations to summarize the reactions taking place in each of the experiments I to 3. (7 marks)
View Ans12. (a) Which ways are the fossil fuels detrimental to the environment? Give four points.
View Ans(b) Briefly explain how biogas is produced by using domestic waste. (7 marks)
View AnsSECTION C (15 Marks)
Answer one (1) question from this section.
13.Explain how to handle chemicals having the warning signs of flammable, corrosive, harmful, explosive and toxic in the laboratory.
View Ans14. Explain six measures for minimizing the environmental degradation caused by extraction of metals in Tanzania.
View Ans