The oxidation states of iron atoms in compounds (A), (B) and (C), respectively, are x, y and z. The sum of x, y and z is ________.

Na₄[Fe(CN)₅(NOS)]
       (A)

Na₄[FeO₄]
       (B)

[Fe₂(CO)₉]
       (C)

The number of chiral carbons present in the molecule given below is _____ .

The Gibbs change (in J) for the given reaction at
[Cu²⁺] = [Sn²⁺] = 1 M and 298K is :

Cu(s) + Sn²⁺(aq.) $$ \to $$ Cu²⁺(aq.) + Sn(s);

($$E_{S{n^{2 + }}|Sn}^0 = - 0.16\,V$$,
$$E_{C{u^{2 + }}|Cu}^0 = 0.34\,V$$)
Take F = 96500 C mol^–1)

The increasing order of the following compounds towards HCN addition is :