Question

3. One litre of water at 30°C is mixed with one litre of water at 50° C. The temperature of the mixture will be (a) 80°C (b) More than 50°C but less than 80°C (c) 20° C (d) Between 30°C and 50°C​

Answer 1

Answer:

b option is correct mark me as brainlist

Answer 2

Correct option is

D

between 30C and 50C

Let the first volume of water be V1. Let the second volume of water be V2. Let the initial temperature of the first volume of water be θ1. Let the initial temperature of the second volume of water be θ2.

Let the energy required to heat a unit volume of water by unit temperature by C.

So, if the final temperature is θfinal, we have

heat gained by the first volume of water

=V1×C×(θfinal−θ1)

and

heat lost by the second volume of water

=V2×C×(θ2−θfinal).

By the law of conservation of energy,

heat lost = heat gained

∴V1×C×(θfinal−θ1)=V2×C×(θ2−θfinal)

∴V1θfinal−V1θ1=V2θ2−V2θfinal

∴θfinal=V1θ1+V2θ2V1+V2

Substituting the given values,

θfinal=2

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