Practice question

Given: A 0.2 kg aluminium block at 120° C is placed in 0.8 kg of water at 20° C in a 0.1 kg copper calorimeter at 20° C . What is the final temperature? (Specific heat of aluminium = 900 J kg^{-1 K^{-1, water = 4186 J kg^{-1 K^{-1, copper = 386 J kg^{-1 K^{-1 ) These values define the system as per NCERT data. Formula: Heat lost = Heat gained. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: 0.2 × 900 × (120 - T) = (0.8 × 4186 + 0.1 × 386) × (T - 20) . 21600 - 180 T = (3348.8 + 38.6) × (T - 20) = 3387.4 T - 67748 . 21600 + 67748 = 3387.4 T + 180 T . 89348 = 3567.4 T Rightarrow T approx 25.04° C approx 25° C . 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.