ANS:C - 2N

To solve this problem, let's first establish the relationship between the volume and the number of molecules for a given gas under standard conditions (temperature and pressure). According to Avogadro's law, equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. Given that 1 Nm^3 of O2 contains 'N' number of molecules, then the number of molecules in 2 Nm^3 of O2 will also be 'N'. Now, let's consider SO2. Since the question doesn't specify any change in conditions such as temperature or pressure, we can assume that the volume-molecule relationship remains the same. Therefore, if 1 Nm^3 of O2 contains 'N' molecules, then 2 Nm^3 of SO2 will also contain 'N' molecules. So, the number of molecules in 2 Nm^3 of SO2 will be 'N'.