JEE Advanced 2020 · Paper 1, Chemistry question 11

(A) Acid strength rises $\ce{HOCl < HClO3 < HClO4}$, so $\ce{ClO-}$ is the strongest conjugate base. True.

(B) Shapes:

• $\ce{ClO-}$ is diatomic, so it is linear whatever the lone pairs.
• $\ce{ClO3-}$ has one lone pair on Cl, which makes it pyramidal.
• $\ce{ClO4-}$ has none and is tetrahedral.

Only chlorate's shape is set by a lone pair. True.

(C) The two ions disproportionate differently:

• $\ce{3ClO- -> 2Cl- + ClO3-}$;
• $\ce{4ClO3- -> Cl- + 3ClO4-}$.

The products are different sets of ions. False.

(D) $\ce{ClO- + SO3^{2-} -> Cl- + SO4^{2-}}$. True.

(A), (B), (D)