Explanation:
[tex]760 \: mmHg \: = \: 1 \: atm \\ 846 \: mmHg \: = \: ( \frac{846}{760} ) \: atm \\ = 1.1 \: atm \\ \\ P _{1} V _{1} = P _{2}V _{2} \\ 1.1 \times V _{1} = 2.5 \times 63.9 \\ V _{1} = \frac{2.5 \times 63.9}{1.1} \\ V _{1} = 145.2 \: litres[/tex]
