Answer
0.81 L
Work Step by Step
$V_{1}$ = 0.82 L
$T_{1}$ = (26+273)K =299 K
$T_{2}$ = (21+273)K =294 K
According to Charles's Law,
$V_{2}$ = $\frac{V_{1}\times T_{2}}{T_{1}}$ =$\frac{0.82L\times 294K}{299K}$ $\approx$ 0.81 L
We can use 0$^{\circ}$C = 273.15 K for more precise results.