PDF chapter test TRY NOW

Answer the following question:
  
Which of the following materials fall in the category of a “pure substance”?
(a). Ice (b). Milk (c). Iron (d). Hydrochloric acid (e). Calcium oxide (f). Mercury (g). Brick (h). Wood (i). Air.
 
Pure substances in the given list of materials are -
  
(a). Ice ().
(c). Iron ().
(e). Calcium oxide ().
(f). Mercury ().
 
Both milk and hydrochloric acid are homogeneous . Please note that the acid is formed when the vapours of hydrogen chloride gas are passed through water.

Wood and air (containing suspended particles) are heterogeneous . However, air free from any suspended particles is a homogeneous mixture.