AIIMS 2010 Physics Evaporation and Boiling Assertion Reason Question

The assertion states that water kept in an open vessel will quickly evaporate on the surface of the moon. This is true because the moon has a very low atmospheric pressure, which allows water to evaporate rapidly even at lower temperatures. The reason provided states that the temperature at the surface of the moon is much higher than the boiling point of water. This is misleading; while the moon does experience high temperatures during the day, it can also be extremely cold at night, and the lack of atmosphere means that boiling point conditions do not apply in the same way as on Earth. Therefore, both the assertion and reason are true, but the reason does not correctly explain the assertion. Hence, the correct answer is B.

Option A is incorrect because the reason does not accurately explain the assertion. Option C is incorrect because it states that the assertion is true but the reason is false, which is not the case as both are true. Option D is incorrect as both statements are true. Thus, the correct choice is B.