What is the mass of water required to prepare 300 g of a 5% by mass solution of a solute?
Mass of solute = (5/100) × 300 = 15 g . Mass of water = 300 - 15 = 285 g .
Ref: NCERT Class 12 Chemistry > Chapter 1: Solutions > Topic: Colligative Properties - Relative Lowering and Elevation of Boiling Point