Which of the following represents the correct order of decreasing inductive effect:

Options

A. (a)`-overset(oplus)(NH_(3))gt-NO_(2)gt-Br`
B. (b)`-overset(oplus)(NH_(3))gt-Brgt-NO_(2)`
C. (c)`-Brgt-NO_(2)gt-overset(oplus)NH_(3)`
D. (d)`-NO_(2)gt-Brgt-overset(oplus)NH_(3)`

Answer

To determine the correct order of decreasing inductive effect among the given groups (NH3, NO2, and Br), we can follow these steps:

### Step 1: Understand Inductive Effect
The inductive effect refers to the permanent polarization of a bond due to the electronegativity difference between atoms. Electron-withdrawing groups exhibit a negative inductive effect (-I), while electron-donating groups exhibit a positive inductive effect (+I).

### Step 2: Identify the Groups
In this question, we are given three groups:
- NH3 (Amine group)
- NO2 (Nitro group)
- Br (Bromine)

### Step 3: Determine the Inductive Effect of Each Group
1. **NH3 (Amine)**: This group is electron-donating due to the presence of the nitrogen atom, which has a lone pair of electrons. Thus, it exhibits a positive inductive effect (+I).

2. **NO2 (Nitro)**: This group is a strong electron-withdrawing group due to the highly electronegative oxygen atoms. It exhibits a strong negative inductive effect (-I).

3. **Br (Bromine)**: Bromine is less electronegative than oxygen but still exhibits a weak negative inductive effect (-I) because it can withdraw electron density from the carbon chain.

### Step 4: Compare the Inductive Effects
Now, we can compare the inductive effects:
- NH3 has a positive inductive effect (+I).
- NO2 has a strong negative inductive effect (-I).
- Br has a weak negative inductive effect (-I).

### Step 5: Arrange in Order of Decreasing Inductive Effect
Based on the analysis:
1. NH3 (+I) - strongest
2. NO2 (-I) - stronger than Br
3. Br (-I) - weakest

Thus, the correct order of decreasing inductive effect is:
**NH3 > NO2 > Br**

### Conclusion
The correct answer matches with option A.

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