AIIMS 2018 Physics Newton's Law of Cooling MCQ Question

According to Newton's law of cooling, the rate of heat loss of a body is proportional to the temperature difference between the body and its surroundings. When cooling from 50.0°C to 49.9°C, the temperature difference is 20.0°C (50.0°C - 30.0°C), and it takes 5 seconds. When cooling from 40.0°C to 39.9°C, the temperature difference is 10.0°C (40.0°C - 30.0°C), which is half of the previous difference. Therefore, it will take twice as long to cool through this smaller temperature range, resulting in a time of 10 seconds. Options A (2.5 s), C (20 s), and D (5 s) do not accurately reflect the proportional relationship dictated by Newton's law of cooling.