Question

Mercury is closer to the Sun than the Venus. But Venus is hotter than Mercury. This is because
A. mercury has no atmosphere and venus has thick atmosphere which can retain the heat
B. mercury is mostly made up of sedimentary rocks while venus contains igneous rocks
C. mercury being closer to sun, sun absorbs the heat of mercury
D. all of the above are true

Answer 1

Hint: Rather than telling mercury has no atmosphere it is ideal to tell mercury has no considerable amount of atmosphere. In case of the moon the gravity is very less such that it can’t hold the atmosphere gases and hence the moon has no atmosphere. Similarly mercury also has less gravity that it can’t withhold its atmosphere. Gravity of mercury is nearly only 40 percent of earth’s gravity. In the case of venus some other property plays a key role in maintaining its hot temperature.

Complete answer:

The reasons why mercury has no atmosphere is because of its low gravity, hot temperature gases and heavy solar winds.
Due to the small size of mercury it has low gravity and it can’t hold atmosphere so that they escape and when temperature is hotter gases in the atmosphere get heated and reach space easily. But venus is still hotter than mercury because of its thicker atmosphere.
Venus is having an atmosphere which is 90 times thicker than earth's atmosphere and has greenhouse gases like carbon dioxide which stores a lot of heat.
Hence even though mercury is closer to the sun, venus is hotter than mercury.

So answer would be option A.

Note:
Mercury also has a thin layer of atmosphere. It contains gases like hydrogen, nitrogen and oxygen which absorbs heat and at the same time releases heat but in case of greenhouse gases like carbon dioxide they store heat a lot. These greenhouse gases are responsible for global warming on earth. Hence both mercury and venus are not suitable for human living.