Understanding Pure Substances and Mixtures

What is the primary difference between elements and compounds?

• Elements are always metals, while compounds are always non-metals.

• Elements can be separated by physical means, while compounds cannot.

• Elements are always solid, while compounds are always liquid.

• Elements are made of one type of atom, while compounds are made of two or more types of atoms.

Which of the following is an example of a colloid?

• Saltwater

• Paint

• Pure sodium

• Oil and water

How do the particles in pure substances compare to those in mixtures?

• Pure substances have the same size particles as mixtures.

• Pure substances have no particles.

• Pure substances have larger particles than mixtures.

• Pure substances have smaller particles than mixtures.

What is the appearance of colloids compared to solutions?

• Colloids are homogeneous, while solutions are heterogeneous.

• Both colloids and solutions are homogeneous.

• Both colloids and solutions are heterogeneous.

• Colloids are heterogeneous, while solutions are homogeneous.

Which separation technique is used for solutions like seawater?

• Distillation

• Filtration

• Decantation

• Centrifugation

What is the process of separating hydrogen and oxygen in water called?

• Decantation

• Centrifugation

• Distillation

• Electrolysis

Which method is used to separate colloids?

• Filtration

• Decantation

• Centrifugation

• Distillation

How can you determine if a liquid sample is a pure substance or a mixture?

• By testing its color

• By testing its boiling point

• By testing its viscosity

• By testing its density

What happens to the temperature of a pure liquid during boiling?

• It fluctuates randomly.

• It decreases.

• It increases steadily.

• It remains constant.

Which of the following is true about the melting of pure substances?

• They do not melt at all.

• They melt completely and smoothly.

• They melt at varying temperatures.

• They melt only under high pressure.