Which of the following is the strongest oxidizing agent?

Arrange the following set of compounds in order of their decreasing relative reactivity with an electrophile,$E^{+}$:
$(a)$ Chlorobenzene,$2,4-$dinitrochlorobenzene,$p-$nitrochlorobenzene
$(b)$ Toluene,$p-CH_3-C_6H_4-NO_2$,$p-O_2N-C_6H_4-NO_2$

$K_1, K_2$ and $K_3$ are the equilibrium constants of the following reactions $(I), (II)$ and $(III)$,respectively :
$(I) \ N_2 + 2O_2 \rightleftharpoons 2NO_2$
$(II) \ 2NO_2 \rightleftharpoons N_2 + 2O_2$
$(III) \ NO_2 \rightleftharpoons \frac{1}{2}N_2 + O_2$
The correct relation from the following is

The first,second and third Ionisation energies ($E_1, E_2$ and $E_3$) for an element are $7 \ eV, 12.5 \ eV$ and $42.5 \ eV$ respectively. The most stable oxidation state of the element will be

$A$ particle moves in a straight line with retardation proportional to its displacement. Its loss of kinetic energy for any displacement $x$ is proportional to

The following configuration of gates is equivalent to