The cell potential for the given cell at 298 K

Pt| H₂ (g, 1 bar) | H⁺ (aq) || Cu²⁺ (aq) | Cu(s)

is 0.31 V. The pH of the acidic solution is found to be 3, whereas the concentration of Cu²⁺ is 10^$$-$$x M. The value of x is ___________.

(Given : $$E_{C{u^{2 + }}/Cu}^\Theta $$ = 0.34 V and $${{2.303\,RT} \over F}$$ = 0.06 V)

A dilute solution of sulphuric acid is electrolysed using a current of 0.10 A for 2 hours to produce hydrogen and oxygen gas. The total volume of gases produced a STP is _____________ cm³. (Nearest integer)

[Given : Faraday constant F = 96500 C mol^$$-$$1 at STP, molar volume of an ideal gas is 22.7 L mol^$$-$$1]

For the given reactions

Sn²⁺ + 2e^$$-$$ $$\to$$ Sn

Sn⁴⁺ + 4e^$$-$$ $$\to$$ Sn

the electrode potentials are ; $$E_{S{n^{2 + }}/Sn}^o = - 0.140$$ V and $$E_{S{n^{4 + }}/Sn}^o = + 0.010$$ V. The magnitude of standard electrode potential for $$S{n^{4 + }}/S{n^{2 + }}$$ i.e. $$E_{S{n^{4 + }}/S{n^{2 + }}}^o$$ is _____________ $$\times$$ 10^$$-$$2 V. (Nearest integer)

The quantity of electricity in Faraday needed to reduce 1 mol of Cr₂O$$_7^{2 - }$$ to Cr³⁺ is ____________.