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.
(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.
Show Hint
- (a) and (b) only
- (a) only
- (b) only
- (b) and (c) only
The Correct Option is C
Solution and Explanation
(b) In HCl, \(\mathrm{MnO_4^-}\) oxidises \(\mathrm{Cl^-}\) to \(\mathrm{Cl_2}\), so part of the permanganate is consumed and the titration is not satisfactory (dilute H2SO4 is used instead). Statement (b) is incorrect.
(c) Some lanthanoid oxides (e.g. of Eu, Y) are used as phosphors in colour television screens. Statement (c) is correct.
Only (b) is incorrect.
Answer: (3) (b) only
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