Liquid water is believed to be the key to the development of life as we know it (LAWKI). So, for a planet to have liquid water, there must be water and the temperature must fall within some fairly narrow temperature band.
Yup, there is (see next page)
The temperature is determined by a balance between Solar heating and the Cooling Rate. We have,
Mars is very cold and, in fact, the current conditions on Mars are such liquid cannot exist on its surface,
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The atmospheric pressure on Mars is ~0.006 atm, and althugh it is not so clear from the phase diagram, H2 is expected to be mostly solid (ice) or vapor (gas) for the current conditions on Mars.