Identify the correct statement from the foolowing.
(i) In the oxidation of oxalic acid with `KMnO_(4)` in acid medium, `Mn^(2+)` acts as auto catalyst.
(ii) CdS colloidal solution can be precipited by the addition of `C1^(-)`ions.
(iii) The gold number of three protective colloids (A, B, C) is 0.03,25 and 0.25 respectively. Their protective power follows the order `A gt C` gt B.
(iv) Physisorption is an irreversible process.

Options

A. (i), (iv)
B. (ii), (iii)
C. (i), (iii)
D. (i), (ii), (iii)

Answer

C

Explanation

(i) Oxidation of oxalic acid with `KMnO_(4)` in acid medium, `Mn_(2+)` acts as auto catalyst. So, this statement is correct.
(ii) CDS colloidal solution can be precipitated by the addition of `Cl^(-)` ions. This statement is incorrect.
(iii) The gold numbers of three protective colloids (A, B, C) is 0.03, 25 and 0.25 respectively.
Their protective power follows the order `A gt C gt B` so the statement is correct.
Physisorption is not an irreversible process.