A pre-weighed vessel was filled with oxygen gas at NTP and weighed. It was then completely evacuated — States of Matter and Gaseous State Chemistry Question

💡 Solution & Explanation

According to Avogadro's law and the ideal gas equation ($PV = nRT$), equal volumes of gases at the same temperature and pressure contain an equal number of moles. Therefore, $n_{O_2} = n_{SO_2} \implies W_{O_2}/32 = W_{SO_2}/64 \implies W_{O_2} = (32/64)W_{SO_2} = 0.5 W_{SO_2}$.