Class 9 · Science · Exploration

9. Atomic Foundations of Matter

Try question 1

The atomic number of an element is the number of

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Answer and explanation

Answer: B. protons

Atomic number (Z) equals the number of protons in the nucleus.

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Try question 2

The chemical symbol of sodium is

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Answer and explanation

Answer: C. Na

Na comes from its Latin name, natrium.

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Try question 3

A molecule of oxygen gas (O₂) contains

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Answer and explanation

Answer: B. two atoms

Oxygen is diatomic.

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