The question above is incomplete, the options attached to the question are listed below:
A.
Hydrogen effuses 1.4 times faster than helium.
B.
Hydrogen effuses 0.71 times faster than helium.
C.
Helium effuses 1.4 times faster than hydrogen.
D.
Helium effuses 0.71 times faster than hydrogen.
E.
The rate of effusion of both gases is the same.
ANSWER
The correct answer is D.
The rate of effusion of an element refers to the rate at which a gas will escape through a small role. The effusion rate of a gas is inversely proportional to the square root of the mass of its particles.
Effusion rate = rate of hydrogen / rate of helium
Effusion rate = 2^1/2 /4^1/2 = 1/2^1/2
Effusion rate = square root of 1/2 = 0.71.
