Question 17
Quantity of Heat250 g of lead at 170°C is dropped into 100 g of water at 0°C. If the final temperature is 12°C, the specific heat of lead is (specific heat capacity of water is 4,200 J/kg°C)
- A.39.5 J/kg°C
- B.50.4 J/kg°C
- C.127.6 J/kg°C
- D.154.6 J/kg°C
- E.173.4 J/kg°C.
Show the answer and explanation
Answer: C (127.6 J/kg°C)
Explanation
Heat lost by lead = heat gained by water: 0.25 × c × 158 = 0.1 × 4200 × 12 = 5040, so c = 5040/39.5 ≈ 127.6 J/kg°C.