The increasing order of electron donating inductive effect of alkyl groups is

Options

A. `-H lt -CH_(3) lt -C_(2)H_(5) lt -C_(3)H_(7)`
B. `-Hgt-CH_(3)gt-C_(2)H_(5)gt-C_(3)H_(7)`
C. `-H lt -C_(2)H_(5) lt -CH_(3) lt -C_(3)H_(7)`
D. `-H gt -C_(2)H_(5) gt -CH_(3) gt -C_(3)H_(7)`

Explanation

To determine the increasing order of electron donating inductive effect of alkyl groups, we need to analyze the electron donating ability of different alkyl groups based on their structure and size. Here’s a step-by-step solution:

### Step 1: Understand Inductive Effect
The inductive effect refers to the permanent polarization of the electron density along a chain of atoms in a molecule. Alkyl groups can donate electron density through the inductive effect, which is generally positive (denoted as +I) for alkyl groups.

### Step 2: Identify Alkyl Groups
We need to consider the alkyl groups mentioned in the question:
- Methyl group (–CH₃)
- Ethyl group (–C₂H₅)
- Propyl group (–C₃H₇)

### Step 3: Compare the Alkyl Groups
The electron donating ability of alkyl groups increases with the number of carbon atoms due to the increase in the number of hydrogen atoms attached, which can donate electrons through the inductive effect.

1. **Methyl Group (–CH₃)**: This group has the least number of carbon atoms and therefore has the weakest electron donating inductive effect.
2. **Ethyl Group (–C₂H₅)**: This group has one more carbon than the methyl group, leading to a stronger electron donating effect compared to the methyl group.
3. **Propyl Group (–C₃H₇)**: This group has two more carbons than the methyl group, resulting in the strongest electron donating inductive effect among the three.

### Step 4: Establish the Order
Based on the analysis, we can establish the increasing order of electron donating inductive effect as follows:
- Methyl (–CH₃) < Ethyl (–C₂H₅) < Propyl (–C₃H₇)

### Final Answer
The increasing order of electron donating inductive effect of alkyl groups is:
**–CH₃ < –C₂H₅ < –C₃H₇**