To solve the question, we need to analyze the assertion and the reason provided.
### Step 1: Understand the Compounds
We have two compounds to compare:
1. **N,N-Diethylethanamine** (C2H5)2NH
2. **N,N-Dimethylmethanamine** (CH3)2NH
### Step 2: Identify the Basicity
Basicity in amines is influenced by the availability of the lone pair of electrons on the nitrogen atom. The more electron-donating groups attached to the nitrogen, the more basic the amine tends to be.
### Step 3: Analyze the Electron-Donating Effects
- **N,N-Diethylethanamine** has two ethyl groups (C2H5), which have a +I (inductive) effect. The +I effect of ethyl groups is stronger than that of methyl groups.
- **N,N-Dimethylmethanamine** has two methyl groups (CH3), which also have a +I effect, but it is weaker than that of ethyl groups.
### Step 4: Compare the +I Effects
- The +I effect of ethyl (C2H5) is greater than that of methyl (CH3). This means that N,N-Diethylethanamine will have a greater electron density around the nitrogen atom compared to N,N-Dimethylmethanamine.
### Step 5: Conclusion on Basicity
Since N,N-Diethylethanamine has a stronger +I effect due to the presence of ethyl groups, it will be more basic than N,N-Dimethylmethanamine.
### Step 6: Evaluate the Assertion and Reason
- **Assertion**: N,N-Diethylethanamine is more basic than N,N-Dimethylmethanamine. (True)
- **Reason**: +I effect of ethyl is more than methyl. (True)
Since both the assertion and reason are true, and the reason correctly explains the assertion, the correct answer is that both are true, and the reason is the correct explanation for the assertion.
### Final Answer
The correct option is **A**: Both assertion and reason are true, and the reason is the correct explanation of the assertion.
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