For the following electrochemical cell at 298 K

Pt(s) | H₂ (g, 1 bar) | H⁺ (aq, 1 M) || M⁴⁺ (aq), M²⁺ (aq) | Pt (s)

E_cell = 0.092 V when $${{\left[ {{M^{2 + }}(aq)} \right]} \over {\left[ {{M^{4 + }}(aq)} \right]}}$$ = 10^x

Give, $$E_{{M^{4+}}/{M^{2 + }}}^o$$ = 0.151 V; 2.303 RT/F = 0.059 V

The value of x is

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 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

The electrochemical cell shown below is a concentration cell. M | M²⁺ (saturated solution of a sparingly soluble salt, MX₂) || M²⁺ (0.001 mol dm^–3) | M The emf of the cell depends on the difference in concentrations of M²⁺ ions at the two electrodes. The emf of the cell at 298 K is 0.059 V.

The solubility product (K_sp; mol³ dm^–9) of MX₂ at 298 K based on the information available for the given concentration cell is (take 2.303 $$\times$$ R $$\times$$ 298/F = 0.059 V)