Question

Which gas has the lowest rate of diffusion?

• A. ${\mathrm{H}}_2$
• B. ${\mathrm{N}}_2$
• C. ${\mathrm{F}}_2$
• D. ${\mathrm{O}}_2$

Answer 1

The correct option is C

${\mathrm{F}}_2$

Explanation for correct answer:-

Option (C) ${\mathrm{F}}_2$

• According to Graham’s law, the rate of effusion or diffusion of a gas is inversely proportional to the square root of its molar mass.
• Florine has the highest molar mass among these gases. Hence, its rate of diffusion is the lowest.

Explanation for incorrect answer:-

Option (A) Hydrogen:

• It has the lowest molar mass among these gases.
• Hence, its rate of diffusion is the fastest.

Option (B) Nitrogen:

• It is the second lightest gas among these gases.
• Hence, its rate of diffusion is slower than that of hydrogen but faster than the rest.

Option (D) Oxygen:

• It is the third lightest gas among these gases.
• Hence, its rate of diffusion is slower than that of hydrogen and nitrogen but faster than fluorine.

Hence, Option c is correct.