What is not true about borax ?

Options

A. Molecular formula is `Na_(2)B_(4)O_(7). 10H_(2)O`.
B. Crystallic borax contains tetranuclear unit of `[B_(4)O_(5)(OH)_(4)]^(2-)`.
C. It hydrolyses to give an acidic solution.
D. White crystalline solid.

Explanation

To determine what is not true about borax, we will analyze each statement provided in the question step by step.

### Step 1: Analyze the first statement
**Statement:** The molecular formula is Na2B4O7·10H2O.

**Analysis:** This statement is true. The molecular formula for borax is indeed Na2B4O7·10H2O, which indicates that it contains sodium (Na), boron (B), oxygen (O), and water of crystallization (10H2O).

### Step 2: Analyze the second statement
**Statement:** Crystalline borax contains a tetra nuclear unit of B4O5(OH)4^2-.

**Analysis:** This statement is also true. Borax does contain a tetra nuclear unit represented by the formula B4O5(OH)4^2-. This indicates the presence of boron and oxygen in a specific structural arrangement.

### Step 3: Analyze the third statement
**Statement:** It hydrolyzes to give an acidic solution.

**Analysis:** This statement is not true. When borax (Na2B4O7) hydrolyzes, it produces a basic solution, not an acidic one. The hydrolysis reaction leads to the formation of sodium hydroxide (NaOH) and a weak acid (H2B4O7), resulting in an alkaline solution.

### Step 4: Analyze the fourth statement
**Statement:** It is a white crystalline solid.

**Analysis:** This statement is true. Borax is indeed a white crystalline solid, which is a common characteristic of many salts.

### Conclusion
After analyzing all the statements, the one that is not true about borax is: **"It hydrolyzes to give an acidic solution."**

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