Amines

To address the provided statements about the basicity of ethylamine compared to ammonia, we need to consider both the assertion and the reason:

Ethylamine is indeed a stronger base than ammonia. This is because the ethyl group in ethylamine has an electron-donating nature, which increases the electron density on the nitrogen atom. This increased electron density makes it easier for ethylamine to donate a pair of electrons, enhancing its basicity compared to ammonia.

The statement suggests that the I effect (inductive effect) of the ethyl group is responsible for the increased basicity. However, this is incorrect because the ethyl group actually shows a I effect, meaning it donates electrons rather than withdrawing them. The positive inductive effect contributes to the electron-donating property, strengthening the base.

Based on this, while the assertion about ethylamine's basicity is correct, the reason provided is incorrect. The increased basicity is due to the I effect of the ethyl group rather than the I effect.

Therefore, the correct answer is: A is correct but R is incorrect.