Q71 / 180 · NEET 2026 (Cancelled) · Chemistry
Match List I with List II :
List I (Order of reaction) List II (Unit of rate constant) A. Zero order I. $\text{mol}^{-1}\ \text{L}\ \text{s}^{-1}$ B. First order II. $\text{mol}^{-2}\ \text{L}^{2}\ \text{s}^{-1}$ C. Second order III. $\text{s}^{-1}$ D. Third order IV. $\text{mol}\ \text{L}^{-1}\ \text{s}^{-1}$
Choose the correct answer from the options given below :
| List I (Order of reaction) | List II (Unit of rate constant) |
|---|---|
| A. Zero order | I. $\text{mol}^{-1}\ \text{L}\ \text{s}^{-1}$ |
| B. First order | II. $\text{mol}^{-2}\ \text{L}^{2}\ \text{s}^{-1}$ |
| C. Second order | III. $\text{s}^{-1}$ |
| D. Third order | IV. $\text{mol}\ \text{L}^{-1}\ \text{s}^{-1}$ |
Choose the correct answer from the options given below :
- AA-IV, B-II, C-I, D-III
- Correct answerBA-IV, B-III, C-I, D-II
- CA-IV, B-III, C-II, D-I
- DA-I, B-II, C-III, D-IV
Solution
The unit of rate constant $k$ for an $n$-th order reaction is given by $(\text{mol}\ \text{L}^{-1})^{1-n}\ \text{s}^{-1}$.
For zero order reaction ($n=0$):
Unit $= (\text{mol}\ \text{L}^{-1})^{1-0}\ \text{s}^{-1} = \text{mol}\ \text{L}^{-1}\ \text{s}^{-1}$ (Matches A with IV)
For first order reaction ($n=1$):
Unit $= (\text{mol}\ \text{L}^{-1})^{1-1}\ \text{s}^{-1} = \text{s}^{-1}$ (Matches B with III)
For second order reaction ($n=2$):
Unit $= (\text{mol}\ \text{L}^{-1})^{1-2}\ \text{s}^{-1} = \text{mol}^{-1}\ \text{L}\ \text{s}^{-1}$ (Matches C with I)
For third order reaction ($n=3$):
Unit $= (\text{mol}\ \text{L}^{-1})^{1-3}\ \text{s}^{-1} = \text{mol}^{-2}\ \text{L}^{2}\ \text{s}^{-1}$ (Matches D with II)
Therefore, the correct matching is A-IV, B-III, C-I, D-II.
Answer: A-IV, B-III, C-I, D-II
For zero order reaction ($n=0$):
Unit $= (\text{mol}\ \text{L}^{-1})^{1-0}\ \text{s}^{-1} = \text{mol}\ \text{L}^{-1}\ \text{s}^{-1}$ (Matches A with IV)
For first order reaction ($n=1$):
Unit $= (\text{mol}\ \text{L}^{-1})^{1-1}\ \text{s}^{-1} = \text{s}^{-1}$ (Matches B with III)
For second order reaction ($n=2$):
Unit $= (\text{mol}\ \text{L}^{-1})^{1-2}\ \text{s}^{-1} = \text{mol}^{-1}\ \text{L}\ \text{s}^{-1}$ (Matches C with I)
For third order reaction ($n=3$):
Unit $= (\text{mol}\ \text{L}^{-1})^{1-3}\ \text{s}^{-1} = \text{mol}^{-2}\ \text{L}^{2}\ \text{s}^{-1}$ (Matches D with II)
Therefore, the correct matching is A-IV, B-III, C-I, D-II.
Answer: A-IV, B-III, C-I, D-II
Hence, the correct answer is option: 'B'.