Consider the following reactions, (i) 12 N_2(g) + 12 O_2(g) NO(g); _rH^ = 90 kJ ,mol^ -1 (ii) NO(g) + 12 O_2(g) NO_2(g); _rH^ = -74 kJ ,mol^ -1 Select the correct statement about the given reaction.

MHT CET Chemistry question

Consider the following reactions,

(i) \mathrm{\tfrac12 N_2(g) + \tfrac12 O_2(g) \to NO(g);\ \Delta_rH^{\ominus} = 90\ kJ\,mol^{-1}}

(ii) \mathrm{NO(g) + \tfrac12 O_2(g) \to NO_2(g);\ \Delta_rH^{\ominus} = -74\ kJ\,mol^{-1}}

Select the correct statement about the given reaction.

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

Answer: (B)

Reaction (i) has kJ, so energy is absorbed in forming NO, which makes NO energy-rich and unstable; reaction (ii) has kJ, so energy is released

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Question ID VK-064781