2 litres of a gas is enclosed in a vessel at a pressure of 760 mm Hg. If temperature remains constant, calculate pressure when volume changes to 4 dm³.

V₁ = 2 lits.

P₁ (Initial pressure) = 760 mm Hg

V₂ = 4 dm³

P₂ (Final pressure) = ?

By Boyle's Law:

$\text{P}$1 \text{V}1 = \text{P}2 \text{V}2

Substituting the values :

$760 \times 2 = \text{P}$2 \times 4 \\[1em] \text{P}2 = \dfrac{760 \times 2}{4} \\[1em] \text{P}_2 = 380 \text{ mm Hg}

∴ Final pressure of the gas = 380 mm Hg.