BOD values (in ppm) for clean water (A) and polluted water (B) are expected respectively :

The structure of product C, formed by the following sequence of reactions is :

Consider the following cell reaction :

$$C{d_{(s)}} + H{g_2}S{O_{4(s)}} + {9 \over 5}{H_2}{O_{(l)}}$$ $$\rightleftharpoons$$ $$CdS{O_4}.{9 \over 5}{H_2}{O_{(s)}} + 2H{g_{(l)}}$$

The value of $$E_{cell}^0$$ is 4.315 V at 25$$^\circ$$C. If $$\Delta$$H$$^\circ$$ = $$-$$825.2 kJ mol^$$-$$1, the standard entropy change $$\Delta$$S$$^\circ$$ in J K^$$-$$1 is ___________. (Nearest integer) [Given : Faraday constant = 96487 C mol^$$-$$1]

The molarity of the solution prepared by dissolving 6.3 g of oxalic acid (H₂C₂O₄.2H₂O) in 250 mL of water in mol L^$$-$$1 is x $$\times$$ 10^$$-$$2. The value of x is _____________. (Nearest integer) [Atomic mass : H : 1.0, C : 12.0, O : 16.0]