Consider the following statements

I. In the conversion of $\mathrm{O}_2$ to $\mathrm{O}_2^{2+}$ bond order decreases.

II. In the conversion of $\mathrm{O}_2$ to $\mathrm{O}_2^{2+}$ magnetic property is not changed.

III. In the conversion of $\mathrm{O}_2$ to $\mathrm{O}_2^{2+}$ bond length decreases.

IV. $\mathrm{O}_2^{2-}$ and $\mathrm{B}_2$ have same bond order.

Identify the correct statements

The RMS velocity of dihydrogen is $\sqrt{7}$ times more than that of dinitrogen. If $T_{\mathrm{H}_2}$ and $T_{\mathrm{N}_2}$ are the temperatures of dihydrogen and dinitrogen, then the correct relationship between them is

Which of the following solution has highest amount of solute?

At 298 K , the enthalpy change ( in kJ ) for the reaction given below is

$$ \mathrm{CH}_4(g)+\mathrm{O}_2(g) \longrightarrow \mathrm{C}(s)+2 \mathrm{H}_2 \mathrm{O}(l) $$

$$ \begin{aligned} Given:\mathrm{H}_2(g)+\frac{1}{2} \mathrm{O}_2(g) & \longrightarrow \mathrm{H}_2 \mathrm{O}(l) ; \Delta H^{\ominus}=-286 \mathrm{~kJ} \\ \mathrm{C}(s)+\mathrm{O}_2(g) & \longrightarrow \mathrm{CO}_2(g) ; \Delta H^{\ominus}=-394 \mathrm{~kJ} \\ \mathrm{CH}_4(g)+2 \mathrm{O}_2(g) & \longrightarrow \mathrm{CO}_2(g)+2 \mathrm{H}_2 \mathrm{O}(l) \Delta H^{\ominus}=-890 \mathrm{~kJ}\end{aligned} $$