Question

Assertion : A hydrogen filled balloon stops rising after it has attained a certain height in the sky.

Reason : The atmospheric pressure decreases with height and becomes zero when maximum height is attained.

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not correct explanation of A

(c) A is true but R is false

(d) A and R are false

Answer 1

Correct option (c) A is true but R is false

Explanation :

Initially balloon rises and density of air goes on decreasing with height. Hydrogen is lighter than air and the hydrogen balloon rises till its density becomes equal to that of surrounding atmosphere or we can say that the pressure exerted by its weight and air displaced becomes equal.