The silver Salt of a Monobasic acid on ignition gave 60% of Ag. The molecular mass of the acid is

Options

A. 37
B. 33
C. 73
D. 77

Explanation

To solve the problem, we need to determine the molecular mass of a monobasic acid from the information given about its silver salt. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Problem
We know that the silver salt of a monobasic acid yields 60% of silver upon ignition. This means that if we take a certain amount of the silver salt, 60% of that mass will be silver.

### Step 2: Set Up the Mass Relationship
Let’s assume we take 100 grams of the silver salt. According to the problem, 60 grams of silver (Ag) will be produced upon ignition.

### Step 3: Calculate the Mass of the Silver Salt
Since 60 grams of silver comes from 100 grams of the silver salt, the mass of the silver salt can be represented as:
- Mass of silver salt = Mass of silver + Mass of the acid part
- Mass of silver = 60 grams
- Mass of the acid part = 100 grams - 60 grams = 40 grams

### Step 4: Determine Equivalent Mass of Silver Salt
The equivalent mass of silver (Ag) is 108 grams (since the atomic mass of silver is 108 g/mol). The equivalent mass of the silver salt can be calculated using the formula:
\[ \text{Equivalent mass of silver salt} = \frac{\text{Mass of silver salt}}{\text{Mass of silver left}} \]
Substituting the values:
\[ E = \frac{100 \, \text{g} \times 108 \, \text{g/mol}}{60 \, \text{g}} = 180 \, \text{g} \]

### Step 5: Calculate Equivalent Mass of the Acid
For a monobasic acid, the equivalent mass (E) is related to the molecular mass (M) by the formula:
\[ E = \frac{M}{\text{Basicity}} \]
Since the acid is monobasic, the basicity is 1. Therefore:
\[ E = M \]
From the previous calculation, we have:
\[ E = 180 \, \text{g} \]

### Step 6: Calculate the Molecular Mass of the Acid
Since the equivalent mass of the acid is equal to its molecular mass (because of the basicity of 1), we find that:
\[ M = 180 \, \text{g} \]

### Final Answer
The molecular mass of the acid is **180 grams**.