Which statement is an example of a physical change? 

A)  A chunk of coal is burned to produce carbon dioxide. 
B)  In the troposphere, sulphur dioxide and water vapour reacts to produce sulphuric acid. 
C)  A plant converts carbon dioxide into carbohydrate. 
D)  Confetti is cut from pieces of paper.

What protects humans from air pollution? 

A)  special cells with arm-like extensions that capture small particles 
B)  walking away from the direction of the wind 
C)  a screen-like mesh of fibres within the lung tissue 
D)  tiny, mucus-coated, hairlike structures called cilia