NCERT Question 8 - Chapter 4 Class 7 - Heat

One litre of water at 30°C is mixed with one litre of water at 50°C. The temperature of the mixture will be

1. 80°C (b) more than 50°C but less than 80°C
2. 20°C (d) between 30°C and 50°C

Answer:

Heat flows from objects at higher temperatures to objects at lower temperatures .

• When the two are mixed, heat will flow to 30°C water from 50°C water .
• So the 50°C water will lose heat (reduce temperature), while 30°C water will increase in temperature .

So, the correct answer is (d) The temperature of the mixture will be between 30°C and 50°C.