There is almost no hydrogen in our atmosphere because hydrogen is very light so it will rise until the weight of the hydrogen and upthrust by it becomes equal, moon dosen't have atmosphere because it dosen't have gravity to hold it
because there is gravitational force
Isn't it surprising that Hydrogen which is the most abundant element in the universe is almost absent in the Earth's atmosphere ? The reason for this is that hydrogen being the lightest element has the lowest molecular mass and highest molecular speed and diffusivity. At room temperature a small fraction of hydrogen molecules can reach escape speed and leave the atmosphere permanently. When this process continues over millions of years the concentration of the hydrogen in the atmosphere falls to almost nil , as is the case with the Earth. To have hydrogen in the atmosphere the escape speed should be large, as is the case of Jupiter. The Moon has no atmosphere due to it's low escape speed. In fact the composition of the atmosphere is an indicator of the size of the planet. Greater the fraction of lighter gases in it's atmosphere , larger is the planet.
Our Moon doesn’t have an atmosphere because it is too small and doesn’t have a strong magnetic field. Any atmosphere it might have had would be stripped away by the solar wind that barrages the small world.
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YOU SHOULD KNOW THAT HYDROGEN IS PRESENT IN OUR ENVIRONMENT. AND ATMOSPHERE IS NOT PRESENT IN moon because it don't have gravity to hold gases.
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