At what temperature, the volume of ‘V’ of a certain mass of gas at $\text{37°C}$  will be doubled, keeping the pressure constant

Let us consider initial volume as

${\text{V}}_1=\text{V}$  

If final volume of gas to be double to the initial volume, then

${\text{V}}_{\text{2}}=2\text{V}$

${\text{T}}_1=37°\text{C = 37+273 = 310}\text{K}$

According to Charles’s law,

   $\frac{{\text{V}}_{\text{1}}}{{\text{T}}_{\text{1}}}=\frac{{\text{V}}_{\text{2}}}{{\text{T}}_{\text{2}}}\Rightarrow \frac{\text{V}}{310}=\frac{\text{2V}}{{\text{T}}_2}$

$\Rightarrow {\text{T}}_2=310\times 2=620\text{K}$

Final temperature in degree Celcius $=620-273=347°\text{C}$