(a) Below is a simplified diagram of the Downs Cell used for the manufacture of sodium.
Study it and answer the questions that follow

(i) What material is the anode made of? Give a reason 
(ii) What precaution is taken to prevent chlorine and sodium from re- combination? 
(iii) Write an ionic equation for the reaction in which chlorine gas is formed 
(b) In the Downs process, (used for manufacture of sodium), a certain salt is added to lower the melting point of sodium chloride from about 800°C to about 600°C.
(i) Name the salt that is added 
(ii) State why it is necessary to lower the temperature 
(c) Explain why aqueous sodium chloride is not suitable as an electrolyte for the manufacture of sodium in the Downs process 
(d) Sodium metal reacts with air to form two oxide. Give the formulae of two oxides

(a) The list below shows the formulae of some organic compounds. Use it to answer the questions that follow.

In an experiment, a piece of magnesium ribbon was cleaned with steel wool. 2.4 g of the clean magnesium ribbon was placed in a crucible and completely burnt in oxygen. After cooling, the product weighed 4.0 g
(a) Explain why it was necessary to clean the magnesium ribbon 
(b) What observation was made in the crucible after burning 
(c) Why was there an increase in mass? 
(d) Write the equation for the reaction which took place in the crucible 
(e) The product in the crucible was shaken with water and filtered. Explain the observation which was made when blue and red litmus papers were dropped into the filtrate.

(a) An atom Q can be represented as

What does the number 52 represent? 
(b) Study the information in the table below and answer the equations that follow
(Letters are not the actual symbols of the elements)

(i) Write the formula of the compound formed when N reacts with P. (atomic numbers are N = 20; P = 17) 
(ii) Identify the elements which belong to the third period of the periodic table. Explain 
(iii) Which of the element identified in b (ii) above comes first in the third period? Explain 
(iv) Select two elements which are non- metals
(c) The table below gives some properties of substances I, II, III, and IV. Study it and answer the questions that follow

​(i) What type of bonding exists in substances I and II 
I
II
(ii) Which substances is likely to be sulphur? Explain

(a) The table below shows the standard reduction potentials for four half- cells.
Study it and answer the questions that follow. (Letters are not the actual symbols of the elements)

​(i) Identify the electrode at which oxidation takes place 
(ii) Give a reason why it is necessary to acidify the water 
(iii) Explain why hydrochloric acid is not used to acidify the water 
(c) During electrolysis of aqueous copper (II) sulphate, 144750 coulombs of electricity were used.
Calculate the mass of copper metal that was obtained Cu = 64 ; 1 Faraday = 96500 coulombs)

(a) Name one raw material which sodium hydroxide is manufactured 
(b) Sodium hydroxide pellets were accidentally mixed with sodium chloride 17.6 g of the mixture were dissolved in water to make one litre of solution. 100 cm3 of the mixture were dissolved in water to make one litre solution. 100cm3 of the solution was neutralized by 40cm3 of 0.M sulphuric acid
(i) Write an equation for the reaction that took place
(ii) Calculate the:
(i) Number of moles of the substance that reacted with sulphuric acid 
(ii) Number of moles of the substances that would react with sulphuric acid in the one litre of solution 
(iii) Mass of the unreacted substances in one litre of solution 
(H = 1,0 ; Na = 23.0 ; Cl= 35.5 ; 0= 16.0)
(c) The diagram below shows an incomplete set-up used to prepare and collect ammonia gas

​(i) Name solid M 
(ii) Complete the diagram to show how a dry sample of ammonia gas can be collected
(d) In an experiment, excess ammonia gas passed over heated copper (II) oxide on a combustion tube.
(i) State the observation that was made in the combustion tube at the end of the experiment 
(ii) What property of ammonia is shown in the above reaction 
(iii) Name one use of ammonia

(a) The diagram below shows spots of pure substance A,B, and C on a chromatography paper. Spot D is that of a mixture

After development, A, B and C were found to have moved 8cm, 3cm and 6 cm respectively. D has separated into two spots which had moved 6cm and 8 cm
(i) On the diagram
I Label the baseline ( origin) 
II Show the positions of all the spots after development 
(ii) Identify the substances present in the mixture D 
(b) Describe how solid ammonium chloride can be separated fro a solid mixture of ammonium chloride and anhydrous calcium chloride 
(c) The table shows liquids that are miscible and those that are immiscible

Use the information given to answer the questions that follow
(i) Name the method that can be used to separate L1 and L3 from a mixture of two
(ii) Describe how a mixture of L2 and L4 can be separated

​When a hydrocarbon was completely burnt in oxygen, 4.2g of carbon dioxide and 1.71 g of water were formed. Determine the empirical formula of the hydrocarbon
(H= 1.0 ; C=12.0 ; 0 = 16.0)

When a current of 0.82A was passed for 5 hours through an aqueous solution of metal Z, 2.65 g of the metal were deposited. Determine the charge on the ions of metal Z. ( 1 Faraday = 96500 Coulombs:
Relative atomic mass of Z = 52

When a few drops of aqueous ammonia were added to copper (II) nitrate solution, a light tube precipitate was formed. On addition of more aqueous ammonia, a deep blue solution was formed.
Identify the substance responsible for the:
a. Light blue precipitate 
b. Deep blue solution

In an experiment, a gas jar containing most sulphur dioxide was inverted over another gas jar containing hydrogen sulphide gas
a. State and explain the observation that was made 
b. State the precaution that should be taken when carrying out this experiment 

The set – up below was used to obtain a sample of iron

Write two equations for the reactions which occur in the combustion tube

Study the flow chart below and answer the questions that follow

(a) Identify N and P 
N…………………………………………………………………………………
P ………………………………………………………………………………
(b) What name is given to the type of halogenations/ chlorination reaction in step 2?

The diagram below shows a set- up that was used to prepare and collect a sample of nitric acid

a. Give a reason why it is possible to separate nitric acid from sulphuric acid in the set – up 
b. Name another substance that can be used instead of potassium nitrate
c. Give one use of nitric acid