Calculate the number of hydrogen atoms in 0.25 mole of H₂SO₄.

1 mole of hydrogen atom has 2 x 6.023 x 10²³ atoms.

∴ 0.25 mole will have

$= \dfrac{2 \times 6.023 \times 10^{23}}{1} \times 0.25 \\[0.5em] = 0.5 \times 6.023 \times 10^{23} \text{ atoms}$

Hence, number of hydrogen atoms in 0.25 mole of H₂SO₄ = 0.5 x 6.023 x 10²³ particles