Practice question

Given: A 1.2 M solution of KCl has a density of 1.1 g/mL. What is its molality? (Molar mass of KCl = 74.5 g/mol) These values define the system as per NCERT data. Formula: Mass of 1 L = 1100 g. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Mass of KCl = 1.2 × 74.5 = 89.4 g. Mass of water = 1100 - 89.4 = 1010.6 g = 1.0106 kg. Molality = 1.2 / 1.0106 ≈ 1.187 m ≈ 1.19 m. Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.