Ideal gas equation    $PV=nRT=\frac{w}{M}RT$

where M =molecular weight

w=4.4gm, T=273k , R=0.082,  P=0.82atm  V=2.73litre

$$\begin{gathered} \Rightarrow 0.82\times 2.73=\frac{4.4}{M}\times 0.082\times 273 \\ \Rightarrow M =\frac{4.4\times 0.082\times 273}{.82\times 2.73}= 44 \end{gathered}$$

CO₂ molecular weight is 44