Question

Match List-I with List-II. 

List-I	Order of reaction
A	Zero order
B	First order
C	Second order
D	Third order

 

List-II	Unit of rate constant
I	mol⁻¹ L s⁻¹
II	mol⁻² L² s⁻¹
III	s⁻¹
IV	mol L⁻¹ s⁻¹

• A. A-IV, B-III, C-II, D-I
• B. A-IV, B-III, C-I, D-II
• C. A-IV, B-II, C-I, D-III
• D. A-I, B-II, C-III, D-IV

Hint:

Unit of rate constant depends on order: zero order \(=\text{mol L}^{-1}\text{s}^{-1}\), first order \(=\text{s}^{-1}\), second order \(=\text{L mol}^{-1}\text{s}^{-1}\).

Answer 1

The Correct Option is B

Step 1: Recall general unit of rate constant.
For a reaction of order \(n\): \[ \text{Unit of }k=(\text{concentration})^{1-n}\text{time}^{-1} \]

Step 2: Unit for zero order reaction.
For zero order: \[ n=0 \] \[ k=(\text{mol L}^{-1})^{1}\text{s}^{-1} \] \[ k=\text{mol L}^{-1}\text{s}^{-1} \] So: \[ A-IV \]

Step 3: Unit for first order reaction.
For first order: \[ n=1 \] \[ k=(\text{mol L}^{-1})^0\text{s}^{-1} \] \[ k=\text{s}^{-1} \] So: \[ B-III \]

Step 4: Unit for second order reaction.
For second order: \[ n=2 \] \[ k=(\text{mol L}^{-1})^{-1}\text{s}^{-1} \] \[ k=\text{L mol}^{-1}\text{s}^{-1} \] So: \[ C-I \]

Step 5: Unit for third order reaction.
For third order: \[ n=3 \] \[ k=(\text{mol L}^{-1})^{-2}\text{s}^{-1} \] \[ k=\text{L}^{2}\text{mol}^{-2}\text{s}^{-1} \] So: \[ D-II \] Therefore: \[ A-IV,\quad B-III,\quad C-I,\quad D-II. \]