Arrange the following amines in the order of decreasing basic character in gaseous phase:

(A) \(NH_3\)

(B) \((CH_3)_3N\)

(C) \((CH_3)_2NH\)

(D) \(CH_3NH_2\)

Choose the correct answer from the options given below:

\((CH_3)_3N, (CH_3)_2NH, CH_3NH_2, NH_3\)

The correct answer is option 2. \((CH_3)_3N, (CH_3)_2NH, CH_3NH_2, NH_3\).

The basicity of amines depends on the availability of the lone pair of electrons on the nitrogen atom. Electron-donating groups, such as alkyl groups, increase the basicity of an amine by stabilizing the resulting ammonium ion formed after accepting a proton.

Let us explain the order of decreasing basic character in the gaseous phase based on the provided correct answer:

B. Trimethylamine \((CH_3)_3N\): This is a tertiary amine with three methyl (\(CH_3\)) groups attached to the nitrogen atom. The presence of three alkyl groups increases the electron density around the nitrogen atom, making it more basic compared to other amines.

C. Dimethylamine \((CH_3)_2NH\): This is a secondary amine with two methyl groups attached to the nitrogen atom. Although it is not as basic as trimethylamine, it is still more basic than methylamine and ammonia due to the presence of two alkyl groups.

D. Methylamine \(CH_3NH_2\): This is a primary amine with one methyl group attached to the nitrogen atom. While it is less basic than dimethylamine and trimethylamine, it is still more basic than ammonia due to the presence of the alkyl group.

A. Ammonia \(NH_3\): This is the least basic among the amines listed because it does not have any alkyl groups attached to the nitrogen atom. While ammonia can still act as a base by accepting a proton to form ammonium ion (\(NH_4^+\)), it is less basic compared to the amines with alkyl groups.

In summary, the order of decreasing basic character in the gaseous phase is determined by the number of alkyl groups attached to the nitrogen atom in the amine molecule. More alkyl groups lead to greater electron density around the nitrogen atom, resulting in increased basicity.

Based on this analysis, the order of decreasing basic character in the gaseous phase would be: \((CH_3)_3N\) > \((CH_3)_2NH\) > \(CH_3NH_2\) > \(NH_3\)