Answer: 0.04 atm
Step-by-step explanation:
Boyle's Law: This law states that pressure is inversely proportional to the volume of the gas at constant temperature and number of moles.
(At constant temperature and number of moles)
where,
= initial pressure of gas = 0.12 atm
= final pressure of gas = ?
= initial volume of gas =

= final volume of gas = 7.14 L

Therefore, the final pressure of the air within the balloon is 0.04 atm.