Question

A solid object is placed in water contained in an adiabatic container for some time. The temperature of water falls during this period and there is no appreciable change in the shape of the object. The temperature of the solid object
(a) must have increased
(b) must have decreased
(c) may have increased
(d) may have remained constant

Answer 1

Option (a) is correct answer

Explanation:  

• As the walls of container are adiabatic then there must be no exchange of heat with the surroundings. The temperature of water falls.

• We also know that temperature is transferred from one body to another body(from body at higher temperature to the body at lower temperature)

  Heat loss = heat gain

• Heat is lost by water so it must be absorbed by the container as there is no heat flow in the surroundings.

• Thus the temperature of object must have increased hence option (a) is correct.

Answer 2

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Option A is correct

hope it help