The half life periods of four reactions labelled by A,B, C & D are 30 sec, 4.8 in, 180 sec and 16 min respectively. The fastest reaction is

Options

A. A
B. B
C. C
D. D

Answer

To determine which of the four reactions (A, B, C, D) is the fastest based on their half-life periods, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Half-Life Periods**:
- Reaction A: 30 seconds
- Reaction B: 4.8 minutes
- Reaction C: 180 seconds
- Reaction D: 16 minutes

2. **Convert All Half-Life Periods to the Same Unit**:
- Convert minutes to seconds for reactions B and D.
- Reaction B: \(4.8 \text{ minutes} \times 60 \text{ seconds/minute} = 288 \text{ seconds}\)
- Reaction D: \(16 \text{ minutes} \times 60 \text{ seconds/minute} = 960 \text{ seconds}\)

3. **List All Half-Life Periods in Seconds**:
- Reaction A: 30 seconds
- Reaction B: 288 seconds
- Reaction C: 180 seconds
- Reaction D: 960 seconds

4. **Compare the Half-Life Periods**:
- The half-life periods in seconds are:
- A: 30 seconds
- B: 288 seconds
- C: 180 seconds
- D: 960 seconds
- The smallest half-life period indicates the fastest reaction.

5. **Determine the Fastest Reaction**:
- Among the half-life periods, 30 seconds (Reaction A) is the smallest.

6. **Conclusion**:
- The fastest reaction is Reaction A.

### Final Answer:
The fastest reaction is **A**.