Match the statement given in List-I with statements given in List-II
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List-I |
List-II |
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(A) Catalysts alter the rate of reaction |
(I) cannot be fraction or zero |
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(B) Molecularity |
(II) by lowering the activation energy |
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(C) Second half life of a first order reaction |
(III) is the same as the first |
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(D) e-Ea/RT |
(IV) refers to the fraction of molecules with energy equal to or greater than activation energy |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A)-(II), (B)-(I), (C)-(III), (D)-(IV)
The list collects four basic ideas of chemical kinetics: how a catalyst acts, what molecularity is, the half-life of a first order reaction and the meaning of the exponential term of the Arrhenius equation.
(A) Catalysts alter the rate of reaction — This matches (II) by lowering the activation energy. A catalyst provides an alternative pathway with a lower energy barrier, so more molecules can cross it; it is given back unchanged at the end.
(B) Molecularity — This matches (I) cannot be fraction or zero. Molecularity is the number of species that must collide at the same time in an elementary step, so it is always a whole number: 1, 2 or (rarely) 3. Order, which is found by experiment, can be zero or a fraction.
(C) Second half life of a first order reaction — This matches (III) is the same as the first. For a first order reaction the half-life does not depend on the starting concentration:
\( \displaystyle t_{1/2} = \frac{0.693}{k} \)
so going from 100% to 50% takes the same time as going from 50% to 25%.
(D) e-Ea/RT — This matches (IV) refers to the fraction of molecules with energy equal to or greater than activation energy. In the Arrhenius equation \( k = A\,e^{-E_a/RT} \), the factor \( e^{-E_a/RT} \) is the fraction of molecules that have at least the energy \( E_a \).
Shortcut: (A)-(II) with (B)-(I) appears in Options (1) and (4); (C)-(III) then leaves only Option (1).