Question

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

(d) between 30°C and 50°C

using, $Q=ms\Delta \theta ;where\Delta \theta =T_2-T_1$

One litre of water at higher temperature mixes with same amount of water at lower temperature then due to temperature difference heat flow, as the result the temperature of mixer will range lesser than 50 C but more than 30 C

Heat is transmitted from the hotter object to the colder object till the temperatures of both the objects become equal. Therefore, the temperature will be between 30°C and 50°C.