What mass of `NaCl ("molar mass" =58.5g mol^(-1))` be dissolved in `65g` of water to lower the freezing point by `7.5^(@)C`? The freezing point depression constant `K_(f)`, for water is `1.86 K kg mol^(-1)`. Assume van't Hoff factor for `NaCl` is `1.87`.

Explanation

To solve the problem of determining the mass of NaCl that must be dissolved in 65 g of water to lower the freezing point by 7.5°C, we can follow these steps:

### Step 1: Understand the Freezing Point Depression Formula
The formula for freezing point depression is given by:
\[ \Delta T_f = K_f \times m \times i \]
Where:
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