If 300 ml of a gas at 27⁰ C is cooled to 7⁰ C at constant pressure, its final volume will be
a) 135 ml
b) 540 ml
c) 350 ml
d) 280 ml

Answer: d
Explanation: At constant pressure
\[\frac{V_{1}}{T_{1}} = \frac{V_{2}}{T_{2}} \Rightarrow \frac{300}{300}=\frac{V_{2}}{280}\]     or V₂ = 280 ml