The incorrect statement(s) among (a) - (c) is (are)

(a) W(VI) is more stable than Cr(VI).

(b) In the presence of HCl, permanganate titrations provide satisfactory results.

(c) Some lanthanoid oxides can be used as phosphors.

Among the following compounds, which one has the shortest C – Cl bond?

In the following reaction sequence, [C] is :

The number of chiral centres present in threonine is ________.