The unit of length convenient on the atomic scale is known as an angstrom and is denoted by Å: 1 Å = 10-10 m. The size of a hydrogen atom is about 0.5 Å. What is the total atomic volume in m3 of a mole of hydrogen atoms?

Radius of hydrogen atom, r = 0.5 Å= 0.5 ×10-10 m

Volume of hydrogen atom = 43πr3

= 43 × 227 × 0.5 × 10-103
= 0.524 × 10-30 m3

According to Avogadro’s hypothesis, one mole of hydrogen contains :
N = 6.023 x 1023 atoms
So, Atomic volume of 1 mole of hydrogen atoms,
V=N X Volume of hydrogen atom ,
or, V= 6.023 x 1023 x 0.524 x 10-30
= 3.156 x 10-7m3 ≅ 3 x 10-7 m3