Arrange the following groups in the increasing order of `+M` :
(i) `-ICl,-F,-Br" (ii) "-NH_(2),-OH,-O^(Theta)`

Answer

To solve the problem of arranging the given groups in increasing order of their +M (mesomeric) effect, we will analyze each group step by step.

### Step 1: Understanding +M Effect
The +M effect refers to the mesomeric effect, which involves the delocalization of electrons through pi bonds or lone pairs. Groups that can donate electron density through resonance will exhibit a +M effect. The stronger the ability to donate electron density, the greater the +M effect.

### Step 2: Analyzing the First Set of Groups: `-ICl, -F, -Br`
1. **Identify the Groups**: The groups are -I (Iodine), -Cl (Chlorine), -F (Fluorine), and -Br (Bromine).
2. **Electronegativity and Size**:
- Fluorine is the most electronegative and has the smallest size, allowing for better overlap with carbon's p-orbitals.
- Chlorine is less electronegative than fluorine but more than bromine and iodine.
- Bromine is less electronegative than chlorine and has a larger size.
- Iodine is the least electronegative and has the largest size.
3. **Order of +M Effect**:
- Fluorine has the highest +M effect due to its strong ability to donate electrons.
- Chlorine follows, then bromine, and finally iodine has the lowest +M effect.

**Result for First Set**:
- Increasing order of +M effect: **-I < -Br < -Cl < -F**

### Step 3: Analyzing the Second Set of Groups: `-NH2, -OH, -O-`
1. **Identify the Groups**: The groups are -NH2 (Amino), -OH (Hydroxyl), and -O- (Oxygen with a negative charge).
2. **Comparing Electron Donating Ability**:
- The -O- group has a negative charge, indicating it has excess electron density and can donate electrons very effectively, giving it the highest +M effect.
- The -NH2 group can also donate electrons, but not as effectively as the -O- group due to nitrogen's lower electronegativity compared to oxygen.
- The -OH group is the least effective in donating electrons because oxygen is more electronegative and holds onto its electrons more tightly than nitrogen.

**Result for Second Set**:
- Increasing order of +M effect: **-OH < -NH2 < -O-**

### Final Answer
Combining both results, we have:
1. For the first set: **-I < -Br < -Cl < -F**
2. For the second set: **-OH < -NH2 < -O-**