A hydrogen inflated polythene balloon is released from the surface of the earth. As the balloon rises to an altitude up in the atmosphere, it will
A
Decrease in size
B
Flatten into a disc-like shape
C
Increase in size
D
Maintain the same size and shape
Correct Answer: Option C
Explanation
1 A hydrogen inflated polythene balloon rises because the density of hydrogen is much lower than the density of the surrounding air, providing buoyancy.
2 As the balloon rises to higher altitudes in the atmosphere, the external atmospheric pressure decreases significantly.
3 The pressure of the hydrogen gas inside the balloon remains relatively higher than the decreasing external pressure.
4 This pressure difference causes the gas inside to expand, pushing the flexible polythene balloon outwards.
5 Consequently, the balloon will increase in size.