Practice question

Given: For the reaction 2A + 3B -> C, the concentration of A decreases from 0.14 M to 0.10 M in 20 seconds. What is the average rate of formation of C in mol L^{-1 s^{-1 ? These values define the system as per NCERT data. Formula: Rate = -1/2 fracΔ[A]Δ t = -1/3 fracΔ[B]Δ t = fracΔ[C]Δ t. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Δ[A] = 0.10 - 0.14 = -0.04 mol L^{-1, Δ t = 20 s . -fracΔ[A]Δ t = 2.0 × 10⁻³, so fracΔ[C]Δ t = frac2.0 × 10⁻³²= 1.0 × 10⁻³. 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.