Which statement about effusion is false?

• A. Effusion can be described by Graham's law.
• B. Effusion occurs faster for heavier gas molecules compared to lighter ones.
• C. Effusion is the process by which gas molecules escape through a tiny hole into a vacuum.
• D. Effusion rate is inversely proportional to the square root of the molar mass of the gas.

Answer: (B)

Verified step by step guidance

1. Understand the concept of effusion: Effusion is the process by which gas molecules escape through a tiny hole into a vacuum. This is a fundamental concept in gas behavior.
2. Learn about Graham's law of effusion: Graham's law states that the rate of effusion of a gas is inversely proportional to the square root of its molar mass. This can be expressed mathematically as: $\frac{r}{R}=\sqrt{\frac{M}{m}}$, where $r$ and $R$ are the effusion rates of two gases, and $M$ and $m$ are their molar masses.
3. Analyze the statement about effusion rates: According to Graham's law, effusion occurs faster for lighter gas molecules compared to heavier ones, because the rate is inversely proportional to the square root of the molar mass.
4. Identify the false statement: The statement 'Effusion occurs faster for heavier gas molecules compared to lighter ones' contradicts Graham's law, which indicates that lighter molecules effuse faster.
5. Conclude the analysis: Based on the understanding of effusion and Graham's law, the false statement is the one suggesting that heavier gas molecules effuse faster than lighter ones.