The physical state of $${X_2}$$ at room temperature changes from gas to solid down the group

Decrease in ionization energy down the group

Decrease in $${\pi ^ * } - {\sigma ^ * }$$ gap down the group

Decrease in HOMO-LUMO gap down the group

(II) (i) (S)

(IV) (ii) (P)

(I) (iv) (Q)

(III) (iv) (R)

The central atom in both $$HCl{O_4}$$ and $$HClO$$ is $$s{p^3}$$ hybridized

$$HCl{O_4}$$ is more acidic than $$HClO$$ because of the resonance stabilization of its anion

$$HCl{O_4}$$ is formed in the reaction between $$C{l_2}$$ and $${H_2}O$$

The conjugate base of $$HCl{O_4}$$ is weaker base than $${H_2}O$$

The work done on the gas is maximum when it is compressed irreversibly from $$\left( {{p_2},{V_2}} \right)$$ to $$\left( {{p_1},{V_1}} \right)$$ against constant pressure $${p_1}$$

If the expansion is carried out freely, it is simultaneously both isothermal as well as adiabatic

The work done by the gas is less when it is expanded reversibly from $${V_1}$$ to $${V_2}$$ under adiabatic conditions as compared to that when expanded reverseibly from $${V_1}$$ to $${V_2}$$ under isothermal conditions

The change in internal energy of the gas is (i) zero, if it is expanded reversibly with $${T_1} = {T_2}$$ , and (ii) positive, if it is expanded reversibly under adiabatic conditions with $${T_1}\, \ne \,{T_2}$$