ANS:C -

The correct time-temperature curve when a block of metal is heated above room temperature and then left to cool in the room following Newton's law of cooling, where the rate of temperature drop decreases with time, would resemble the exponential decay curve. In an exponential decay curve, the temperature of the metal decreases rapidly at first and then gradually approaches room temperature as time progresses. This is consistent with Newton's law of cooling, which states that the rate of heat loss of an object is proportional to the temperature difference between the object and its surroundings. As the temperature difference decreases over time, the rate of cooling also decreases, resulting in a gradual approach to thermal equilibrium with the surroundings. Therefore, the correct representation of the time-temperature curve would be an exponential decay curve, where the rate of temperature drop decreases with the passage of time.