One mole of SO2 combines completely with one mole of Cl2 in the presence of charcoal to give SO2Cl2, which is then hydrolysed completely by excess water to H2SO4 and HCl. The number of moles of NaOH needed to neutralise all the acids formed is

JEE Advanced levelSingle correct optionDifficulty 3 of 3pn088

One mole of $SO X_{2}$ combines completely with one mole of $Cl X_{2}$ in the presence of charcoal to give $SO X_{2} Cl X_{2}$ , which is then hydrolysed completely by excess water to $H X_{2} SO X_{4}$ and $HCl$ . The number of moles of NaOH needed to neutralise all the acids formed is

SO X_{2} + Cl X_{2} SO X_{2} Cl X_{2}

and

SO X_{2} Cl X_{2} + 2 H X_{2} O H X_{2} SO X_{4} + 2 HCl

. 1 mol

H X_{2} SO X_{4}

needs 2 mol NaOH and 2 mol HCl need 2 mol NaOH, giving 4 mol.