What are the safety rules and separation methods in a laboratory, and what is Graham's Law of diffusion?

Here are the answers to the questions:

10. Which of the following is not a safety rule in the laboratory?
C) Always work alone.
Working alone in a laboratory is generally discouraged due to safety concerns, as there would be no one to assist in case of an accident or emergency.

11. What should one do if there is a chemical spill in the laboratory?
A) To inform the laboratory technician.
Informing the laboratory technician or supervisor is the crucial first step for any chemical spill, as they are trained to assess the hazard and direct the appropriate cleanup or emergency procedures.

12. Which of the following is not a method of separating mixtures?
C) A mixture of gases or solids substances.
Sublimation (A) is a method of separating mixtures. Options B, C, and D are descriptions of substances, properties, or types of mixtures, not methods of separation. Option C describes the type of mixture itself, not a process to separate it.

13. State Graham's Law of diffusion.
Graham's Law of diffusion states that the rate of diffusion or effusion of a gas is inversely proportional to the square root of its molar mass (or density).
Mathematically, this can be expressed as:

$$\frac{\text{Rate}_1}{\text{Rate}_2} = \sqrt{\frac{M_2}{M_1}}$$

where $\text{Rate}_1$ and $\text{Rate}_2$ are the rates of diffusion of two different gases, and $M_1$ and $M_2$ are their respective molar masses.