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2019 mokasa chemistry paper 1

This paper consists of 12 printed pages. Candidates are advised to check and to make sure all pages are as
indicated and no question is missing.

State two laboratory rules that should be followed to avoid contamination and wastage of chemicals.                                                                                                                        (2 marks)

 

  1. (a) Give one reason some of the laboratory apparatus are made of ceramics.

(1 mark)

 

(b)       Name two apparatus that can be used to measure approximately 75 cm3 of dilute sulphuric (VI) acid.                                                                                        (2 marks)

The above set-up was used to determine the chemical properties of carbon (II) oxide.

6. A student placed some hydrogen peroxide in a test tube then added a small amount of
manganese (IV) oxide. A glowing splint was then brought near the mouth of the tube.
7. An organic compound with formular ????4????8 , has isomers. Draw and name two possible
structural isomers of the compound. (3 marks)
7. An organic compound with formular ????4????8 , has isomers. Draw and name two possible
structural isomers of the compound. (3 marks)
8. Explain how the compound ????4????8 and ????4????10can be distinguished using bromine water.
(2 marks)
9. a)
     i)State the role of concentrated sulphuric (VI) acid. (1 mark)
     ii)
     iii)
10 (a) State Boyle's law. (1mk)
(b) A gas occupies 270cm3 at a pressure of 660mmHg at 370C. What is the new
volume if pressure is changed to 810 mmHg at 630 C? (2 marks)
11. An organic compound contains 24.24% carbon, 4.04% hydrogen and the rest chlorine. If
its relative molecular mass is 99, what is its molecular formula?(3 marks)
12. A given mass of sodium nitrate was heated completely and 320 cm3 of the gas was
produced at s.t.p.



13. (a) Give one advantage of using methyl orange over phenolphthalein as an indicator.
(1 mark)
14. A tea farmer suspects that her farm had turned acidic. She obtained a soil sample to
analyze for pH. Give her the procedure to follow in order to verify this. (2 marks)
15. Use the diagram below to answer the questions that follow:
(a) Define electrolysis. (1mk)
(c) Write the equation at the anode. (1 mark)
16
(a) Why was the air passed through;
(i) sodium hydroxide solution? (1 mark)
(b) Name the major gas collected in the syringe. (1 mark)
18. Describe how to prepare crystal of magnesium sulphate starting with magnesium
powder. (3 marks)
19

(b)       Name the catalyst which could be used to increase the reaction rate of production

of hydrogen gas in the set up drawn above.                                               (1 mark)

  1. An element consists of two isotopes with atomic masses 59 and 61 in the ratio of 3 : 2 respectively.

(a)       What are isotopes?                                                                                       (1 mark)

  1. An element:

(a)       To which chemical family does it belong?                                                  (1 mark)

  1. The diagram below shows the radiations emitted by a radioactive sample.

Name the radiations;                                                                                    (3 marks)

P          -

M         -

N         -

  1. Calculate the enthalpy of formation of ethanol given the enthalpies of;

combustion of ethanol = -1369 kJ/mole

combustion of carbon = -394kJ/mole

combustion of hydrogen = -286kJ/mole

            (3 marks)

  1. (a) State what is observed when sodium hydroxide pellets are left in air overnight.

(1 mark)

(b)       What name is given the process shown by the salt in (a) above?            (1 mark)

  • Identify;

Solid F -                 (1 mark)

Solid J  -                  (1 mark)

  • Write equation for step 1. (1 mark)

 

2019 MOKASA 2019 BIOLOGY PAPER 2