Compound X has less than 4 carbon atoms. Using the given test results, identify compound X and give its systematic name. Then, give the systematic name for CH3CH(CH3)CH2NH2.

• Test A (PCl₅): No white fumes. This indicates the absence of -OH groups (alcohols or carboxylic acids).
• Test B (Bromine water): No reaction. This indicates the absence of C=C or C≡C double/triple bonds and phenols.
• Test C (2,4-dinitrophenyl hydrazine): Orange precipitate. This indicates the presence of a carbonyl group ($\text{C=O}$), meaning X is either an aldehyde or a ketone.
• Test D (Tollen's Reagent): No reaction. This indicates the absence of an aldehyde group.

From Test C, X is an aldehyde or a ketone. From Test D, X is not an aldehyde. Therefore, X must be a ketone.

Compound X has "less than 4 carbon atoms". The smallest ketone possible has 3 carbon atoms.

The only ketone with less than 4 carbon atoms is propanone.

The identity of compound X is $\boxed{\text{Propanone}}$.

This is a 3-carbon chain (propane).

The amine group is on carbon 1.

There is a methyl group on carbon 2.
The systematic name is $\boxed{\text{2-methylpropan-1-amine}}$.

This is a 3-carbon chain.

For acyl chlorides, the suffix -oic acid is replaced by -oyl chloride.
The systematic name is $\boxed{\text{Propanoyl chloride}}$.