Asample of neon effuses from a container in 77 seconds. the same amount of an unknown noble gas requires 157 seconds. identify the gas.

Argon

Explanation:

To find the amount of an unknown noble gas that requires 157 seconds fo effuse from a container from which a same amount of sample of neon effuses in 77 seconds, you must use Graham's Law of effusion.

Graham's law of effusion states the rate of effusion of a gas is inversely proportional to the square root of the masses of its particles. Mathematically, that is:

Since, the other conditions (amount of gas and container) are the same for both gases, the rates and the times are inversely proportional; this is:

MolarMass₂ = (157 s / 77 s) × MolarMass₁

Molar Mass₁ = 20.180 g/mol

∴ MolarMass₂ = (157 s / 77 s) × 20.180 g/mol = 41  g/mol

        It is argon. The molar mass of argon is 30.948 g/mol. So, argon (Ar) is the answer.