Chemistry Past Questions and Answers

The most common type of chemical reaction which alkanes undergo is

A Substitution
B Addition
C Condensation
D Polymerisation
E Double decomposition

Question 32:

Consider the following exothermic reaction
2SO_2(g) + O_2(g) â†” 2SO_3(g)
If the temperature of the reaction is reduced from 800°C to 500°C, an no other change takes place, then

A The reaction rate increases
B Concentration of SO₃ decreases
C Concentration of SO₃ increases
D SO₂ gas becomes unreactive
E O₃ gas becomes unreactive

Question 33:

If excess zinc is added to a bluish green solution of copper (II) sulphate, and the excess zinc filtered off after completion of reaction, a colourless solution is obtained because

A Both zinc and copper are metals
B The sulphate radical and the zinc ion are divalent
C Zinc is more electropositive than copper
D Both zinc and copper form depositive ions in solution
E Zinc is a reducing agent

Question 34:

Three solutions contain carbonate, sulphate and sulphide ions respectively. One test that will identify just ONE of them completely is by addition to each of them of

A Barium chloride solution
B Dilute hydrochloric acide
C Lead nitrate solution
D Calcium chloride solution
E Sodium hydroxide solution

Question 35:

Two gas cylinders contain ethylene (ethene) and acetylene respectively. One test which can be used to distinguish between them is by

A Passing each gas through bromine water
B Passing each gas through dilute potassium permanganate solution
C Passing each gas through silver nitrate solution
D Treating each gas catalytically with excess hydrogen gas