Question

Give reasons: [3 MARKS]
a) Clothes do not dry quickly on a cloudy day.
b) It is not advisable to fill hydrogen gas in big air balloons.
c) Balloons filled with helium gas float up into the air.

Answer 1

a) 1 Mark
b) 1 Mark
c) 1 Mark

a) There is a large amount of moisture in the air on a cloudy day. So, clothes do not dry quickly on a cloudy day. The rate of evaporation is higher i.e. clothes dry quicker when the air is less humid.
b) Hydrogen is a combustible gas and forms an explosive mixture with air, so it is not advisable to fill hydrogen gas in big air balloons.
c) Since air is much heavier than helium, the air pushes the light helium balloon towards higher altitudes where the air is also lighter.