Sea water, air and soda water: Sea water is a homogeneous mixture of various minerals and salts in water. Air is a homogeneous mixture of nitrogen, oxygen and several other gases. Soda water is a homogeneous mixture of carbon dioxide gas dissolved in water.
Coal, Soil: Heterogeneous solution.Coal and soil may seem as a single phase, but due to their inconsistent composition, they cannot be categorized as solutions.
Thus, the correct options are (b), (c), and (e).
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