Identify the compounds A-E, and answer the following: (i) Is a carboxylic acid derivative? (ii) Produces a red precipitate of copper (I) oxide when boiled with Fehling's solution? (iii) Is isomeric wi

let's identify these organic compounds.

First, let's identify the functional groups and molecular formulas for each compound:

• A: $CH_3COCH_2CH_3$ is Butanone (a ketone). Molecular formula: $C_4H_8O$.
• B: $CH_3CH_2CH_2COOH$ is Butanoic acid (a carboxylic acid). Molecular formula: $C_4H_8O_2$.
• C: $CH_3CH_2CO_2CH_3$ is Methyl propanoate (an ester). Molecular formula: $C_4H_8O_2$.
• D: $CH_3CH_2CH_2CHO$ is Butanal (an aldehyde). Molecular formula: $C_4H_8O$.
• E: $CH_3CH_2OCH_2CH_3$ is Diethyl ether (an ether). Molecular formula: $C_4H_{10}O$.

Now, let's answer each part:

(i) Is a carboxylic acid derivative?
A carboxylic acid derivative is a compound that can be formed from a carboxylic acid. Esters are common carboxylic acid derivatives.
Compound C ($CH_3CH_2CO_2CH_3$) is an ester.

$$\boxed{\text{C}}$$

(ii) Produces a red precipitate of copper (I) oxide when boiled with Fehling's solution?
Fehling's solution is used to test for aldehydes. Aldehydes reduce the $Cu^{2+}$ ions in Fehling's solution to $Cu_2O$, which is a red precipitate. Ketones do not react.
Compound D ($CH_3CH_2CH_2CHO$) is an aldehyde.

$$\boxed{\text{D}}$$

(iii) Is isomeric with compound A?
Isomers have the same molecular formula but different structural formulas.
Compound A has the molecular formula $C_4H_8O$.
Compound D ($CH_3CH_2CH_2CHO$) also has the molecular formula $C_4H_8O$.

$$\boxed{\text{D}}$$

(iv) Could be reduced to a secondary alcohol?
The reduction of a ketone yields a secondary alcohol. The reduction of an aldehyde yields a primary alcohol.
Compound A ($CH_3COCH_2CH_3$) is a ketone. Its reduction would yield butan-2-ol, which is a secondary alcohol.

$$\boxed{\text{A}}$$

(v) Gives a yellow crystalline precipitate when reacted with iodine in basic solution?
This describes the iodoform test. A positive iodoform test (yellow precipitate of iodoform, $CHI_3$) is given by compounds containing a methyl ketone group ($CH_3CO-$) or a methyl carbinol group ($CH_3CH(OH)-$, which can be oxidized to a methyl ketone).
Compound A ($CH_3COCH_2CH_3$) contains a methyl ketone group ($CH_3CO-$).

$$\boxed{\text{A}}$$