Fifty-nine grams of amide is obtained from the carboxylic acid. `RCOOH` on heating with alkali gave `17 gm` of ammonia. The acid is :

Options

A. Formic acid
B. Acetic acid
C. Propionic acid
D. Benzoic acid

Explanation

To solve the problem, we need to determine the carboxylic acid (RCOOH) from which 59 grams of amide is obtained, and that also produces 17 grams of ammonia when heated with alkali.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- The carboxylic acid (RCOOH) reacts with ammonia (NH3) to form an amide (RCONH2) and water (H2O). The reaction can be represented as:
\[ RCOOH + NH3 \rightarrow RCONH2 + H2O \]

2. **Mass of Amide**:
- From the problem, we know that the mass of the amide (RCONH2) formed is 59 grams.

3. **Mass of Ammonia**:
- The reaction with alkali produces 17 grams of ammonia (NH3). This means that during the reaction, 17 grams of ammonia is released.

4. **Molar Mass Calculation**:
- The molar mass of ammonia (NH3) is approximately 17 g/mol. Since we have 17 grams of ammonia, this corresponds to 1 mole of ammonia.
- Therefore, 1 mole of the amide (RCONH2) is also formed, as the stoichiometry of the reaction indicates that 1 mole of carboxylic acid yields 1 mole of amide.

5. **Molar Mass of Amide**:
- The molar mass of the amide (RCONH2) can be calculated using its mass:
\[ \text{Molar mass of amide} = 59 \text{ g/mol} \]

6. **Setting Up the Equation**:
- The molar mass of the amide can be expressed as:
\[ \text{Molar mass of amide} = \text{Molar mass of R} + \text{Molar mass of CO} + \text{Molar mass of NH2} \]
- The molar mass of CO is 12 (C) + 16 (O) = 28 g/mol.
- The molar mass of NH2 is 14 (N) + 1*2 (H) = 16 g/mol.
- Therefore, we can write:
\[ 59 = \text{Molar mass of R} + 28 + 16 \]
- Simplifying this gives:
\[ 59 = \text{Molar mass of R} + 44 \]
- Thus, we find:
\[ \text{Molar mass of R} = 59 - 44 = 15 \text{ g/mol} \]

7. **Identifying R**:
- The molar mass of R is 15 g/mol, which corresponds to the methyl group (CH3).
- Therefore, R = CH3.

8. **Final Structure of the Acid**:
- The carboxylic acid can now be identified as:
\[ RCOOH = CH3COOH \]
- This is acetic acid.

### Conclusion:
The acid is acetic acid (CH3COOH).