waec model questions vol1 2021 physics
Objective • Question 8
Question 8
WAEC_MODEL_QUESTIONS_VOL1
•
2021
A 150 g iron block (specific heat 0.45 J g⁻¹ °C⁻¹) initially at 200 °C is immersed in 200 g of water (specific heat 4.18 J g⁻¹ °C⁻¹) at 25 °C in an insulated container. (a) Find the equilibrium temperature of the system. (b) To raise the temperature of the mixture to 80 °C, steam at 100 °C is introduced and allowed to condense completely. Assuming the latent heat of vaporisation of water is 2260 J g⁻¹ and the specific heat of liquid water is 4.18 J g⁻¹ °C⁻¹, calculate the mass of steam required.
Answer Options
A.
Equilibrium temperature ≈ 30.8 °C; steam required ≈ 20.3 g
B.
Equilibrium temperature ≈ 35.0 °C; steam required ≈ 18.5 g
Correct Answer
C.
Equilibrium temperature ≈ 38.1 °C; steam required ≈ 16.2 g
D.
Equilibrium temperature ≈ 41.2 °C; steam required ≈ 12.9 g
Correct Answer
C
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