Question

Question 1. Why has helium gas replaced hydrogen in weather observation ballons?

Question 2. Why there a pop sound when hydrogen is burnt?

Answer 1

1) Helium gas has replaced hydrogen in weather observation balloons due to explosive nature of hydrogen gas.Often, the balloons containing hydrogen catch fire, so non- explosive helium gas is used instead.

2) Hydrogen gas is explosive and thus it burns with a pop sound.