Question

A hydrogen balloon(0.089kg/cm 3) floats in air but would it float in the atmosphere on Mars, which has a density of 0.020 kg/m3?​

Answer 1

Earth has a dense atmosphere composed of some layers,

1) Troposphere

2)  Stratosphere

3) Mesosphere. ...

4)Thermosphere

5)  Exosphere. ...

But the  Mars’ has  very thin layer of atmosphere . For these reason a hydrogen balloon in Mars would not fly, but can float in Earth's atmosphere. But in Earth a hydrogen balloon can float.