Question

1. which of the following materials is a mixture?

a) air

b) magnesium metal

c) water

d) methane (ch4)

Explanation:

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<reasoning>

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 (\(\text{O}_2\)).

</reasoning>

<answer>
<mcq-correct>(A) Air</mcq-correct>
<mcq-option>(B) Magnesium metal</mcq-option>
<mcq-option>(C) Water</mcq-option>
<mcq-option>(D) Methane (\(\text{CH}_4\))</mcq-option>
</answer>

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Answer:

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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 (\(\text{O}_2\)).

</reasoning>

<answer>
<mcq-correct>(A) Air</mcq-correct>
<mcq-option>(B) Magnesium metal</mcq-option>
<mcq-option>(C) Water</mcq-option>
<mcq-option>(D) Methane (\(\text{CH}_4\))</mcq-option>
</answer>

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