The average molecular speed is gretest in which of the following gas samples?

Options

A. 1.0 mole `N_(2)` at 560 K
B. 0.50 mole of `Ne` at 500 K
C. 0.20 mole `CO_(2)` at 440 K
D. 2.0 mole of `He` at 140 K

Answer

D

Explanation

`bar(v) = ((8 RT)/(pi M))^(1/2)`
(A) `bar(v) (N_(2)) = ((8R xx 560)/(pi xx 28))^(1/2) = ((160R)/(pi))^(1/2)`
(B) `bar(v) (Ne) = ((8R xx 500)/(pi xx 20))^(1/2) = ((200 R)/(pi))^(1/2)`
(C) `bar(v) (CO_(2)) = ((8R xx 440)/(pi xx 44))^(1/2) = ((80 R)/(pi))^(1/2)`
(D) `v (He) = ((8R xx 140)/(pi xx 4))^(1/2) = ((280 R)/(pi))^(1/2)`
Thus, `v (He)` is maximum