Assuming complete dissociation of the salts , calculate the molatity of sodium chloride solution whose elevation in boiling point is numerically equal to the depression in frezing point of 0.02 m aluminium sulphate solution in water `(K_(b) and k_(f)` for water are 0.52 and 1.86 K kg` " mol"^(-1) ` respectively ).

Explanation

To solve the problem, we need to calculate the molality of the sodium chloride (NaCl) solution given that the elevation in boiling point (ΔTb) of the NaCl solution is equal to the depression in freezing point (ΔTf) of the aluminum sulfate (Al2(SO4)3) solution.

### Step-by-Step Solution:

1. **Identify the given data:**
- Molality of aluminum sulfate solution (m_Al2(SO4)3) = 0.02 m
- Van 't Hoff factor (i) for NaCl = 2 (since it dissociates into Na⁺ and Cl⁻)
- Van 't Hoff factor (i) for Al2(SO4)3 = 5 (since it dissociates into 2 Al³⁺ and 3 SO₄²⁻)
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