Neon effuses 1.26 times as fast an an unknown gas at a particular temperature. What is the molar mass of the unknown gas

31.75 amu

Explanation:

Using Graham's equation of effusion as depicted below:

V1/V2 = √m2/√m1

Where; v1 = speed of neon gas

V2 = speed of unknown gas

m1 = molar mass of neon gas

m2 = molar mass of unknown gas

According to this question: v1 = 1.26x, m1 = 20amu, v2 = 1x, m2 = ?

Hence,

1.26x/1x = √m2/√20

1.26/1 = √m2/4.472

√m2 = 4.472 × 1.26

√m2 = 5.635

m2 = 5.635²

m2 = 31.75 amu

Therefore, the molar mass of the unknown gas is 31.75 amu.