Answer:
The correct answer is HOF gas.
Step-by-step explanation:
Based on the given information, the helium atoms effuses three times faster in comparison to the gas X.
The rate of effusion is determined by,
r is inversely proportional to 1/√M, here M is the molecular mass of the gas.
and r is inversely proportional to 1/t, here t is the time taken for effusion.
Thus, t is directly proportional to √M
The molecular mass of He is 4.
tHe = tX/3 (Here tx is the time taken for gas X)
The molecular mass of X is not known.
tX/tHe =√Mx/MHe
3 = √Mx/4
By squaring both the sides we get,
9 = Mx/4
Mx = 36
36 is the molecular mass of gas HOF, that is, (1+16+19 = 36). Hence, the gas X is 36.