Consider the following reactions:
(i) `(1)/(2)N_(2)(g)+(1)/(2)O_(2)(g) to NO(g),Delta_(r)H^(ө)=90" kJ "mol^(-1)`
(ii) `NO(g)+(1)/(2)O_(2)(g) to NO_(2)(g),Delta_(r)H^(ө)=-74" kJ "mol^(-1)`
Select the correct statement about the given reaction.

Options

A. In (i) reaction, `NO(g)` is unstable because the energy is released. The energy is released in (ii) reaction, `NO_(2)(g)` is stable. Unstable NO(g) changes into the stable `NO_(2)(g)`
B. The energy is absorbed in (i) reaction, NO(g) is unstable. As energy is released in the (ii) reaction `NO_(2)(g)` is stable. That's why unstable NO(g) changes into the stable `NO_(2)(g)`
C. Both (a) and (b)
D. none of these

Answer

B

Explanation

In reactionn (i) enerrgy is absorbed hence, NO becomes unstable so in reaction (ii) it transform to `NO_(2)` by releasing energy.