Explanation:
[tex] \frac{P _{1} V _{1} }{T _{2}} = \frac{P _{2} V _{2}}{T _{1}} \\ \frac{(101300 \times 7)}{(21.5 + 273)} = \frac{(101300 \times 4)}{T _{2}} \\ T _{2} = \frac{(405200 \times 294.5)}{(709100)} \\ T _{2} = 168.3 \: kelvin \\ decrease \: in \: temperature = (294.5 - 168.3) \\ = 126.2 \: kelvin[/tex]
