`{:(,"column I",,,"column II"),(,P.,"Zero order reaction",1.,t_(1//2)alpha(1)/([A]_(0))),(,Q.,"First order reaction",2.,t_(100%)=[A]_(0)//k),(,R.,"second order reactions",3.,"Involves at least two reactants"),(,S.,"Pseudo unimolecular reaction",4.,[A]=[A]_(0)e^(-kt)):}`

Options

A. `{:(,P,Q,R,S),(,2,1,4,3):}`
B. `{:(,P,Q,R,S),(,2,4,1,3):}`
C. `{:(,P,Q,R,S),(,2,1,3,4):}`
D. `{:(,P,Q,R,S),(,3,2,1,4):}`

Answer

To solve the problem of matching the items in Column I with those in Column II, we will analyze each reaction type and its corresponding characteristics step by step.

### Step 1: Analyze Zero Order Reaction (P)
- **Definition**: In a zero-order reaction, the rate of reaction is constant and does not depend on the concentration of the reactants.
- **Half-life formula**: The half-life (t_(1/2)) for a zero-order reaction is given by:
\[ t_{1/2} = \frac{[A]_0}{2k} \]
This indicates that the half-life is directly proportional to the initial concentration \([A]_0\).
- **Match**: The correct match for P (Zero order reaction) is option 2, which states that \(t_{100\%} = \frac{[A]_0}{k}\).

### Step 2: Analyze First Order Reaction (Q)
- **Definition**: In a first-order reaction, the rate of reaction depends linearly on the concentration of one reactant.
- **Half-life formula**: The half-life for a first-order reaction is:
\[ t_{1/2} = \frac{0.693}{k} \]
This shows that the half-life is independent of the initial concentration.
- **Integrated rate law**: The concentration at any time \(t\) is given by:
\[ [A] = [A]_0 e^{-kt} \]
- **Match**: The correct match for Q (First order reaction) is option 4, which corresponds to the integrated rate law.

### Step 3: Analyze Second Order Reaction (R)
- **Definition**: A second-order reaction can involve either two reactants or one reactant with a concentration squared.
- **Half-life formula**: The half-life for a second-order reaction is given by:
\[ t_{1/2} = \frac{1}{k[A]_0} \]
This indicates that the half-life is inversely related to the initial concentration \([A]_0\).
- **Match**: The correct match for R (Second order reaction) is option 1, which states that it involves at least two reactants.

### Step 4: Analyze Pseudo Unimolecular Reaction (S)
- **Definition**: A pseudo unimolecular reaction occurs when one reactant is in excess, making its concentration effectively constant.
- **Characteristics**: Although it involves two reactants, one reactant's concentration does not affect the rate of the reaction.
- **Match**: The correct match for S (Pseudo unimolecular reaction) is option 3, which states that it involves at least two reactants.

### Final Matches
- **P** (Zero order reaction) → **2**
- **Q** (First order reaction) → **4**
- **R** (Second order reaction) → **1**
- **S** (Pseudo unimolecular reaction) → **3**

### Summary of Matches
- P → 2
- Q → 4
- R → 1
- S → 3