Aballoon filled with helium gas is found to take 6 hours to deflate to 50% of its original volume. how long will it take for an identical balloon filled with the same volume of hydrogen gas (instead of helium) to decrease its volume by 50%?

Given:
rate of effusion of Helium = 6 hours

Data needed:
Molar mass of hydrogen gas = 2 g/mol
Molar mass of helium gas = 4 g/mol

Assume:
Constant conditions such as temperature and pressure.

Required:
rate of effusion of Hydrogen gas

Solution:

To solve the problem, we can use the formula:

rate of effusion of A/ rate of effusion of B = (molar mass of B/molar mass of A)^1/2

substituting values,

rate of effusion of hydrogen gas/ 6 hours = (4 g/mol/2 g/mol)^1/2

rate of effusion of hydrogen gas = 8.5 hours

The correct answer is  "c".  it is "c" because melting is an endothermic change, and endothermic get's energy from surroundings.