Question

5. What would be the final temperature of a
mixture of 10gm of water at 10°C and
80 gm water at 80°C ?
A) 45
B) 62°C
C) 72.2°C
D) 52.2°C​

Answer 1

Answer:

c)72.2

Explanation:

water(cold)

m=10g

t=10°C

water(hot)

m=80g

t=80°C

c=4.2Jg-¹°C-¹

let final temp be t

heat lost by hot body=heat gained by cold body

mc◇T=mc◇T

80×c×(80-t)=10×c×(t-10)

[specific heat capacityis equal hence cancels out]

80(80-t)=10(t-10)

8(80-t)=t-10

640-8t=t-10

650=9t

t=72.2°C