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Chemistry Paper 1 Question Paper
Chemistry Paper 1
Course:Secondary Level
Institution: Mock question papers
Exam Year:2006
CHEMISTRY THEORY
PAPER 1
JULY /AUGUST - 2004
TIME: 1 ½ HRS
BUNGOMA DISTRICT MOCK EXAMINATION 2004
Kenya Certificate of Secondary Education (K.C.S.E.)
233/1
INSTRUCTIONS TO CANDIDATES
Answer ALL the questions on the spaces provided.
Mathematical tables may be used.
Electronic calculators MUST NOT be used.
1. Study the information given below
Element Protons Neutrons
Q 9 10
R 12 12
S 18 22
T 8 8
(a) Which is the most (1 mark)
(i) Unreactive element
(ii) Reactive non-metal
(b) Write the formula of the compound that would be formed between (1 mark)
(i) Q and T
(ii) T and R
(c) Give the electronic configuration of (1 mark)
(i) An ion of Q
(ii) T-
2. If 6.5g of zinc powder was dropped in excess copper (ii) sulphate solution. What mass of copper would be deposited(Zn = 65, Cu = 64)
(2 marks)
3.(a) Write the formula of a cation whose carbonate, chloride and sulphate is insoluble
(1 mark)
(b) Write an equation between the cation in (a) above and excess sodium hydroxide solution. (1 mark)
4. The set-up below is used to prepare ethyne.
(a) Identify solid A (1 mark)
(b) Give the name and the formula of the fifth member of the homologous series for which ethyne belongs. (2 marks)
Name ....................
Formula .................
5. The table below shows the solubility of three solids P. Q and R.
Solid Cold water Hot water
P soluble soluble
Q insoluble insoluble
R insoluble soluble
How would you obtain pure samples of P and Q from a mixture containing all the three solids. (3 marks)
6. When excess chlorine gas is bubbled through cold dilute sodium hydroxide solution, the resulting solution acts as a bleaching agent.
(a) Write an equation for the reaction between chlorine gas and sodium hydroxide solution. (1 mark)
(b) Explain how the resulting solution acts as a bleaching agent. (2 marks)
7. An isotope 232 90X emits a total of six alpha particles and four beta particles to form isotope Y.
(a) Write a nuclear equation to represent this change. (1 mark)
(b) Element 214 83Bi has a half-life of 40 minutes. What percentage of its original mass remains after 120 minutes? (1 mark)
(c) The diagram below shows how particles from a radioactive source can be distinguished from each other.
Identify the particles P and R (1 mark)
P ...............
R ...............
8. (i) In the electrolysis of Lead (II) bromide, the molten salt is preferred. Why does molten lead (II) bromide conduct electricity but solid lead bromide does not.
(ii) In the electrolysis of lead (II) bromide a current of 5 amperes was passed through the electrolyte for 386 seconds. Calculate the volume of bromine gas
that would be evolved at s.t.p (Molar gas volume at stp = 22.4dm3, 1 Faraday = 96500 coulombs) (2 marks)
9. The diagram below shows how a sample of oxygen may be prepared in a laboratory.
(a) Identify solid B. (1 mark)
(b) Write a balanced equation for the reaction between B and water. (1 mark)
10. Both sodium sulphite and sodium sulphate are white powders. Describe a simple chemical test to distinguish between the two. (2 marks)
11. 240cm3 of methane diffuses through a porous plug in 30 seconds while 180cm3 of gas Y under similar conditions diffuses in t seconds. Given that the R.M.M. of gas Y is
28, find the value of t. (C = 12, H = 1) (2 marks)
12. Describe briefly a test you would carry out to show that water is a compound with the constituents elements in the ratio 2:1. (2 marks)
13. (a) Define saponification. (1 mark)
(B) Explain briefly how you would produce soap from castor oil in the laboratory.
(2 marks)
14. Iron is manufactured by passing a blast of hot air through a mixture of iron ore, coke and limestone.
(i) What is the function of the limestone? (1 mark)
(ii) Name two impurities likely to be present in the ‘pig iron’ formed in the blast furnace. (1 mark)
(iii) Give one effect of these impurities on the physical properties of Iron. (1 mark)
15. A mixture of pentane and propanoic acid was shaken with 0.15M sodium hydroxide solution and allowed to separate as shown in the diagram below.
Name the main components of layer A. Give a reason for the answer. (2 marks)
16. A student set up the apparatus below to study the properties of hydrogen chloride.
Comment on the deflections of the voltmeter needles. (2 marks)
17. What volume of a hydrochloric acid solution containing 0.36g/100cm3 would be required to neutralize a solution which contains 8.5g/dm3 of 97.8% sodium carbonate?
(3 marks
18. Study the flow chart below and answer the questions that follow.
(a) Name the catalyst used in the catalyst chamber. (1 mark)
(b) Write an equation for the reaction which takes place in the catalyst chamber
(1mark)
(c) Why is excess air used in the cooling chamber. (1 mark)
(d) Give one use of nitric acid. (1 mark)
19. The set up below shows the apparatus that can be used for the preparation of carbon dioxide.
(a) Identify solid K. (1 mark)
(b) What is the role of potassium hydrogen carbonate in the set-up above?
(1 mark)
(c) Why is carbon dioxide a better refrigerant than ice? ( 2 marks)
20. When bromine gas reacts with aqueous sodium hydroxide, the equilibrium represented by the equation below is established.
Br2(g)(Reddish Brown) + 2HO-(aq)(Colourless) <-> Br-(aq) + OBr-(aq) + HO2(l)
What observation would be made in the equilibrium mixture if a few drops of hydrochloride acid were added? Explain. (2 marks)
21. State, with reasons the oxidizing agent in the reaction represented by the equation below.
2NH3(g) + 3Cl2(g) -> N2(g) + 6HCl(g) (2 marks)
22. Nitrogen gas and hydrogen gas react in the presence of iron catalyst according to the equation below
N2(g) + 3H2(g) <=> 2NH3(g)
45cm3 of nitrogen gas was mixed with 120cm3 of hydrogen gas and the mixture passed over heated iron catalyst. Which gas was in excess and by what volume? (All volumes were measured at the same temperature and pressure.) (2 marks)
23. (i) Define “electron affinity”. (1 marks)
(ii) How does this vary among the halogens and how does it affect their reactivity.(2 mk)
24. Using dots (.) and crosses (x) to represent outer electrons, draw a diagram which shows the bonding in the PH4+ ion. (atomic numbers P = 15, H = 1)
(2 marks)
25. The equations below represents two processes that take place without any change in temperature.
I. H2O(s) -> H2O(l)
II. CdCl2(s) -> Cd2+(l) + 2CL-(l)
(a) Explain why although heat is required for each process to take place, the temperature remains constant in both cases. (1 mark)
(b) Which of the processes has a higher enthalpy change H? Give a reason. (2 marks)
26. 7.2 g of Iron were mixed with 25.0cm3 of 2M sulphuric acid solution and the mixture stirred until no further change was observed. 4.4g of Iron remained unreacted.
Deduce the equation for this reaction. (Fe=56) (2 marks)
27. Study the flow chart below and answer the questions that follow:
(i) Name substances (2 marks)
K ........ M ..........
N ........... P ..........
(ii) Write a balanced equation for the reaction that took place when solid K was heated in air. (1 mark)
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