Answer
1186 mmHg
Work Step by Step
$P_{1}= 780.\,mmHg$
$T_{1}= (-75+273)K=198\,K$
$T_{2}= (28+273)K=301\,K$
According to Gay Lussac's law, if n and V are constant
$\frac{P_{1}}{T_{1}}=\frac{P_{2}}{T_{2}}$
$\implies P_{2}=\frac{P_{1}T_{2}}{T_{1}}=\frac{780.\,mmHg\times 301\,K}{198\,K}$
$=1186\,mmHg$
