Explanation:
[tex]RFM = 44 \: g \\ 44g \: contain \: 1 \: mole \\ 88g \: will \: contain \: ( \frac{88}{44} \times 1) \\ = 2 \: moles \\ at \: room \: temperature \\ 1 \: mole \: occupies \: 24 \: {dm}^{3} \\ 2 \: moles \: occupies \: (2 \times 24) \\ = 48 \: {dm}^{3} [/tex]