Observe the following statements (I) In the $\mathrm{H}_{2}-\mathrm{O}_{2}$ reaction, explosion occurs when the rate of chain branching exceeds that of chain termination. (II) The order of the reaction, $\mathrm{nA} \rightarrow$ products, is 2.5 . For this reaction, $\mathrm{t}_{1 / 2} \propto[\mathrm{A}]_{0}^{-3 / 2}$ (III) Unimolecular gas phase reactions are second order at low pressure but become first order at high pressure. Which of the following is correct?
(a)I, II and III are correct
(b)Only II is correct
(c)Only III is correct
(d)I and II are correct
Answer
Answer: A ✓ checked by 4AB · confidence high
The source book printed no answer; this one was worked out and checked — see the explanation.
Explanation
(I) Explosion occurs when branching outruns termination. (II) For order n, t½ ∝ [A]₀^(1−n) = [A]₀^(−3/2). (III) The Lindemann mechanism is second order at low pressure and first order at high pressure. All three are correct (a).