The human body does not produce

$A$ photoelectric cell is connected to a source of variable potential difference. The resulting photoelectric current $(\mu A)$ is plotted against the applied potential difference $(V)$. The graph with the broken line represents the data for a given frequency and intensity of the incident radiation. If the frequency is increased and the intensity is reduced, which of the following graphs (represented by unbroken lines) corresponds to the new situation?

Which of the following is incorrect with respect to $Chondrichthyes$?

$A \rightarrow D$ is an endothermic reaction occurring in $3$ steps (elementary).
$(i)$ $A \rightarrow B$ $\Delta H_{i} = +ve$
$(ii)$ $B \rightarrow C$ $\Delta H_{ii} = -ve$
$(iii)$ $C \rightarrow D$ $\Delta H_{iii} = -ve$
Which of the following graphs between potential energy ($y$-axis) vs reaction coordinate ($x$-axis) correctly represents the reaction profile of $A \rightarrow D$?

In Van der Waals equation of state for a non-ideal gas,the term that accounts for intermolecular forces is

For the reaction :
$NH_{3(g)} \rightleftharpoons \frac{1}{2} N_{2(g)} + \frac{3}{2} H_{2(g)}$ ; $K_P$
The degree of dissociation $(\alpha)$ of $NH_3$ is related to total equilibrium pressure $(P^o)$ as: