Answer:
31.75 amu
Step-by-step 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.