Tick (√) the most appropriate answer.
The humans pollute the air by :
(a) burning a vast amount of coal
(b) burning waste materials
(c) using petrol and diesel vehicles
(d) all the above
What is air pollution ? What are the harmful effects of sulphur dioxide, nitrogen dioxide and hydrogen sulphide present in the air ?
Tick (√ ) the most appropriate answer.
Magnesium burns with a dazzling white flame to form magnesium oxide, a powdery mass. The colour of magnesium oxide is : .
(a) milk white