The standard reduction potential data at 25^oC is given below:
E^o (Fe³⁺ , Fe²⁺) = +0.77V;
E^o (Fe²⁺ , Fe) = -0.44V;
E^o (Cu²⁺ , Cu) = +0.34V;
E^o (Cu⁺ , Cu) = +0.52V;
E^o [O₂(g) + 4H⁺ + 4e^- $$\to$$ 2H₂O] = +1.23V;
E^o [O₂(g) + 2H₂O + 4e^- $$\to$$ 4OH^-] = +0.40 V
E^o (Cr³⁺ , Cr) = -0.74V;
E^o (Cr²⁺ , Cr) = -0.91V;

Match E^o of the redox pair in List – I with the values given in List – II and select the correct answer using the code given below the lists:

List - I
P. E^o (Fe³⁺ , Fe)
Q. E^o (4H₂O $$\leftrightharpoons$$ 4H⁺ + 4OH^-)
R. E^o (Cu²⁺ + Cu $$\to$$ 2Cu⁺)
S. E^o (Cr³⁺, Cr²⁺)

List - II
1. -0.18 V
2. -0.4 V
3. -0.04 V
4. -0.83 V

An aqueous solution of X is added slowly to an aqueous solution of Y as shown in List – I. The variation in conductivity of these reactions in List – II. Match List – I with List – II and select the correct answer using the code given below the lists:

List - I
P. $$\mathop {(C{}_2{H_5}){}_3N}\limits_X $$ + $$\mathop {C{H_3}COOH}\limits_Y $$
Q. $$\mathop {KI(0.1M)}\limits_X $$ + $$\mathop {AgN{O_3}(0.01M)}\limits_Y $$
R. $$\mathop {C{H_3}COOH}\limits_X $$ + $$\mathop {KOH}\limits_Y $$
S. $$\mathop {NaOH}\limits_X $$ + $$\mathop {HI}\limits_Y $$

List - II
1. Conductivity decreases then increases
2. Conductivity decreases then does not change much
3. Conductivity increases then does not change much
4. Conductivity does not change much then increases

The thermal dissociation equilibrium of CaCO₃(s) is studied under different conditions

CaCO₃(s) $$\leftrightharpoons$$ CaO(s) + CO₂(g).

For this equilibrium, the correct statement(s) is (are)

The K_sp of Ag₂CrO₄ is 1.1 $$\times$$ 10^-12 at 298 K. The solubility (in mol/L) of Ag₂CrO₄ in a 0.1 M AgNO₃ solution is