(A) \(CO_2\)
Let say, the molar mass of unknown gas is M
Then, Number of mole of unknown gas = \(\frac{4.4\,g}{M}\)
As we know,
1 mole of any gas at STP occupy = 22.4 L of volume.
\(\therefore\) Number of moles unknown gas = \(\frac{2.24}{22.4}=0.1\) mol
Therefore,
\(\frac{4.4}{M}=0.1\)
\(M=\frac{4.4}{0.1}\)
M = 44 g/mol
In the given options only \(CO_2\) has molar mass of 44 g/mol
Hence, the unknown gas will be \(CO_2\).