Practice question

Given: What is the mass percentage of potassium in KMnO₄? (Atomic masses: K = 39, Mn = 55, O = 16) These values define the system as per NCERT data. Formula: Molar mass = 39 + 55 + (4 × 16) = 39 + 55 + 64 = 158 g/mol. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Mass of K = 39 g. % K = (39 / 158) × 100 ≈ 24.68%. 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.