Question

1. which of the following materials is a mixture?

a) air

b) magnesium metal

c) water

d) methane (ch4)

Explanation:

Identify pure substances versus mixtures

• Magnesium metal is an element (\(\text{Mg}\)).
• Water is a compound (\(\text{H}_2\text{O}\)).
• Methane is a compound (\(\text{CH}_4\)).
• Air is a homogeneous mixture of gases, primarily nitrogen (\(\text{N}_2\)) and oxygen (\(\text{O}_2\)).

Answer:

• (A) Air (Correct answer)
• (B) Magnesium metal
• (C) Water
• (D) Methane (\(\text{CH}_4\))