JEE · NEET Previous Year Question

Steam at C is passed into 20g of water at C When water acquires a temperature of C, the mass of water present will be: [ Take specific heat of water = 1 cal and latent heat of steam = 540 cal ]

Topic: NEET PYQ

Answer: D. Full step-by-step solution below.

  1. A24 g
  2. B31.5 g
  3. C42.5 g
  4. D22.5 g

Correct answer: D

Solution

(d) m(g) steam at 100° → m(g) water at 100°C + 540m ......(a)
m(g) water at 100°C → m(g) water at 80°C + (m)(a) (20) ......(b)
(a) + (b)
m(g) steam at 100°C → m(g) water at 80° + 560m (cal) ......(c)
20 g water at 10°C + (20) (a) 70 → 20 g water at 80°C ......(d)
from (c) and (d)
mix + 1400 cal → (20 + m) g water at 80°C + 560m (cal)
1400 = 560m
2.5 = m
Total mass of water present
= (20 + 2.5)g
= 22.5g

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