Question:medium

The unit of length convenient on the atomic scale is known as an angstrom and is denoted by \(\AA\) : 1 \(\AA\) = \(10^{-10}\;\text m\). The size of a hydrogen atom is about 0.5\(\AA .\) What is the total atomic volume in m3 of a mole of hydrogen atoms ?

Updated On: Jan 21, 2026
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Solution and Explanation

Given:

1 angstrom (Å) = 1 × 10−10 m
Size (diameter) of a hydrogen atom = 0.5 Å

Hence, radius of a hydrogen atom:
r = 0.25 Å = 0.25 × 10−10 m

Number of atoms in one mole:
NA = 6.02 × 1023


Step 1: Volume of one hydrogen atom

Assuming a hydrogen atom to be spherical, its volume is:

V1 = (4/3)πr3

V1 = (4/3)π (0.25 × 10−10)3

V1 = (4/3)π × 0.015625 × 10−30

V16.5 × 10−32 m3


Step 2: Total atomic volume of one mole of hydrogen atoms

Vtotal = NA × V1

Vtotal = (6.02 × 1023) × (6.5 × 10−32)

Vtotal3.9 × 10−8 m3


Final Answer:

The total atomic volume of one mole of hydrogen atoms is:
≈ 4 × 10−8 m3

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