Answer:
2.00
Step-by-step explanation:
From Graham's law; the rate of effusion is inversely proportional to the square root of the relative molecular mass.
Let the rate of effusion of Helium be R1
Let the rate of effusion of Methane be R2
Let the molecular mass of Helium be M1
Let the molecular mass of Methane be M2
Hence;
R1/R2 = √M2/M1
R1/R2 = √16.0294/4.0026
R1/R2 = 2.00