Practice question

Given: Calculate the freezing point depression of a solution made by dissolving 6 g of urea ( NH₂CONH₂ ) in 200 g of water. ( K_f = 1.86 K kg/mol, Molar mass of urea = 60 g/mol ) These values define the system as per NCERT data. Formula: Moles of urea = 6/60 = 0.1 mol. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Molality = 0.1/0.2 = 0.5 mol/kg . Δ T_f = 1.86 × 0.5 = 0.93 K . 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.