Answer: m= 22.2 g Ne
Explanation: First find the moles of Ne using Ideal Gas Law and derive for n. So from PV= nRT the mole is derived as n = PV /RT
n = PV / RT
= 1 atm ( 25 L ) / 0.0821 L.atm /
mole.K ( 273 K )
= 1.11 moles Ne
Convert it to mass using the molar mass of Neon
1.11 moles Ne x 20 g Ne / 1 mole Ne
= 22.2 g Ne