Hydrogen balloon rises up in the air because the density of hydrogen is ___.
lesser than air's density
equal to air's density
greater than air's density
None of the above
A balloon filled with___ gas rises in the air because the density of___ gas is less as compared to air.
When the density of air is compared with that of hydrogen chloride, the density of hydrogen chloride is ________ to air.
The density of hot air is_____ than that of cold air.