Which of the following statement is/are wrong?

Options

A. Beilstein test is a reliable test for halogens in organic compounds.
B. In Lassaigne's test for N, Prussian blue colour is due to the formation of ferro-ferri cyanide.
C. When `FeCl_3` solution is added to the Lassaigne's extract, a blue solution is obtained which indicates the presence of both N and S.
D. Molecular mass of an acid `=` Equivalent mass `xx` acidity

Explanation

To determine which statements are wrong, we will analyze each statement one by one based on the information provided.

### Step-by-Step Solution:

1. **Statement 1: Bilstein test is a reliable test for halogens in organic compounds.**
- The Bilstein test is indeed used to detect halogens, but it is not reliable for all halogens. It works for chlorine, bromine, and iodine, but fails for fluorine. Additionally, it can give false positives with other elements like sulfur. Therefore, this statement is **wrong**.

2. **Statement 2: In lessons test for nitrogen, Prussian blue color is due to the formation of ferroferric.**
- The Prussian blue color in the determination of nitrogen is due to the formation of ferric ferrocyanide (Fe₄[Fe(CN)₆]₃), not ferroferric. The correct term is ferri-ferrocyanide. Thus, this statement is also **wrong**.

3. **Statement 3: When FeCl₃ solution is essence extract, a blue solution is obtained, indicating the presence of both nitrogen and sulfur.**
- When both nitrogen and sulfur are present, the addition of neutral FeCl₃ solution results in a blood red color of ferric sulfosinide (Fe(CNS)₃), not a blue solution. Therefore, this statement is **wrong**.

4. **Statement 4: Molecular mass of an acid is equal to equivalent mass into acidity.**
- The term "acidity" is not applicable in this context; it should be "basicity" for acids. Therefore, this statement is also **wrong**.

### Conclusion:
All four statements are incorrect.

**Answer: All statements (1, 2, 3, and 4) are wrong.**

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