Question

What is the SI unit for rate of diffusion?

• A. $cm^3~minute^{-1}$
• B. $dm^3~hour^{-1}$
• C. $dm^3~s^{-1}$
• D. $mL~hour^{-1}$

Hint:

Rate quantities generally have units: \[ \frac{\text{quantity}}{\text{time}} \] For diffusion: \[ \frac{\text{volume}}{\text{time}} \]

Answer 1

The Correct Option is C

Concept:
Rate of diffusion is defined as: \[ \text{Rate of diffusion} = \frac{\text{Volume of gas diffused}}{\text{Time}} \] Hence its unit is: \[ \text{Volume} \div \text{Time} \]

Step 1: Identify SI related units. Standard SI-type units are:
• Volume $\rightarrow m^3$ or $dm^3$
• Time $\rightarrow s$

Step 2: Check the options.
• $cm^3~minute^{-1}$ → not SI time unit
• $dm^3~hour^{-1}$ → hour is not SI unit
• $dm^3~s^{-1}$ → correct SI-compatible form
• $mL~hour^{-1}$ → non-SI units

Step 3: Conclusion. Therefore, the correct unit is: \[ \boxed{dm^3~s^{-1}} \]