During estimation of nitrogen present in an organic compound using Kjeldahl's method, the `NH_3` evolved from 0.25 g of the compound was neutralised by 10 ml of 1.25N `H_2SO_4` What is the percentage of nitrogen in the organic compound?

Options

A. 0.56
B. 0.35
C. 0.7
D. 0.66

Answer

To find the percentage of nitrogen in the organic compound using Kjeldahl's method, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Values**:
- Weight of the organic compound (W) = 0.25 g
- Volume of H₂SO₄ used (V) = 10 ml
- Normality of H₂SO₄ (N) = 1.25 N

2. **Use the Formula for Percentage of Nitrogen**:
The formula to calculate the percentage of nitrogen (N%) in the organic compound using Kjeldahl's method is:
\[ \text{Percentage of Nitrogen} = \frac{1.4 \times N \times V}{W} \]
where:
- N = Normality of the acid
- V = Volume of the acid in ml
- W = Weight of the organic compound in grams

3. **Substitute the Values into the Formula**:
Now we can substitute the known values into the formula:
\[ \text{Percentage of Nitrogen} = \frac{1.4 \times 1.25 \times 10}{0.25} \]

4. **Calculate the Numerator**:
First, calculate the numerator:
\[ 1.4 \times 1.25 \times 10 = 17.5 \]

5. **Calculate the Percentage of Nitrogen**:
Now divide the numerator by the weight of the compound:
\[ \text{Percentage of Nitrogen} = \frac{17.5}{0.25} = 70 \]

6. **Convert to Decimal Form**:
Since the options are in decimal form, convert 70% to decimal:
\[ 70\% = \frac{70}{100} = 0.7 \]

7. **Final Answer**:
Therefore, the percentage of nitrogen in the organic compound is **0.7**.