Answer
$-129^{\circ}$C
Work Step by Step
$V_{1}= 2.50\,L$
$T_{1}=(15+273)=288\,K$
$V_{2}=1250\,mL=1.250\,L$
According to Charles's law,
$\frac{V_{1}}{T_{1}}=\frac{V_{2}}{T_{2}}$
$\implies T_{2}=\frac{V_{2}T_{1}}{V_{1}}=\frac{1.250\,L\times288\,K}{2.50\,L}=144\,K$
$=(144-273)^{\circ}C=-129^{\circ}C$
