Chemistry Past Questions and Answers

A balanced chemical equation obeys the law of

A Conservation of mass
B Definite proportions
C Multiple proportions
D Conservation of energy

Question 42:

When air which contains the gases Oxygen, nitrogen, carbondioxide, water vapour and the rare gases, is passed through alkaline pyrogallol and then over quicklime, the only gases left are;

A Nitrogen and carbondioxide
B The rare gases
C Nitrogen and oxygen
D Nitrogen and the rare gases

Question 43:

In the laboratory preparation of oxygen, the gas cannot be collected by displacement of air because

A The density of oxygen is greater than that of air
B The density of air is nearly the same as that of oxygen
C Oxygen is a component of air
D Air is an impure substance

Question 44:

2KClO3(g) MNO3â†’ 2KCl(s) + 3O2(g)
The importance of the catalyst in the reaction above is that

A Heating may not be required before the reaction takes place
B The reaction is controllable even at a high temperature
C The reaction produces large quantity of oxygen
D The reaction takes place more rapidly at a lower temperature

Question 45:

Which of the following is used to power steam engines?

A Lubricating oil
B Coal
C Bitumen
D Diesel oil