Viva Voce: Solution, Colloids & Suspension | Lab Manuals for Class 9 PDF Download

Q.1. Give one example of gaseous solution.

Air

Q.2. Name the solute and solvent in sugar solution.

Solute → sugar Solvent → water.

Q.3. What is tincture of iodine solution?

A solution of iodine in alcohol is ‘tincture of iodine’.

Q.4. Why does a true solution not scatter a beam of light?

Due to very small particle size, it does not scatter a beam of light.

Q.5. How can you separate colloidal particles from its solution?

By centrifugation

Q.6. Give two examples of Aerosol.

Fog, mist

Q.7. Give two examples of emulsion.

Milk, face cream

Q.8. Give the chemical formula of sugar and alum.

Sugar – sucrose → C1₂H₂₂O₁₁
Alum – K₂S0₄. A₁₂(S0₄)₃.24H₂0

Q.9. What will you name the heterogeneous solution whose particle size is between 10^-7 cm to 10-⁴ cm?

It is a colloidal solution.

Q.10. What is concentration of solution?

The amount of solute present in a given solution.

Q.11. Give two examples of foam.

Shaving cream, rubber

Q.12. Name three types of colloids.

Aerosol, foam, emulsion

Q.13. What is Tyndall effect?

The scattering of beam of light is called Tyndall effect.

Q.14. What is the size of particles in true solution?

The size is less than 1 nm (10^-9 metre) in diameter.

Q.15. Name one solution that has gas as solute.

Soda water, solute is C0₂, solvent is water.

Q.16. Give one example of solid solution.

Alloys: Brass—30% Zinc and 70% copper.

Q.17. Give one example of liquid solution.

lemonade + water

Q.18. What are saturated and unsaturated solutions?

A solution which cannot dissolve more solute at a given temperature is called a saturated solution. A solution which can dissolve more of the solute at a given temperature is called an unsaturated solution.

Q.19. What precaution should you take while preparing starch solution?

We should always prepare starch paste and then dissolve it in hot water.

Q.20. Give one use of suspension.

Suspensions are used in medicines.

Q.21. Give three examples of solvents, commonly used.

Water, acetone, alcohol

Q.22. How can you make a saturated solution unsaturated?

Saturated solution on heating becomes unsaturated.

Q.23. What is the dispersed phase and dispersing medium in foam?

In foam, the dispersing medium is liquid and dispersed phase is gas—for e.g. shaving cream. Alternatively When dispersing medium is solid and dispersed phase is gas then foam is formed for e.g., rubber, sponge.

Q.24. A saturated solution was obtained at 25^°C. What will happen if it is kept in 40^°C condition?

The solution will become unsaturated, because the solubility increases with the rise in temperature.

Q.25. To make a solution, 40 g of common salt is dissolved in 280 g of water. Calculate its concentration in terms of mass by mass percentage of the solution.

Mass of solute = 40 g
Mass of solvent = 280 g
Mass of solution = Mass of solute + Mass of solvent.
= 40 g + 280 g = 320 g
Mass percentage of solution = Mass of solute / Mass of solution x 100
= 40/320 x 100
= 12.5

Q.26. How can you make unsaturated solution saturated?

The unsaturated solution on cooling/freezing can become saturated.

Q.27. Why is water called a universal solvent?

Water is called universal solvent as maximum number of substances dissolve in it.

Q.28. What is dispersed phase and dispersing medium?

The medium in which a colloid is formed is called the dispersing medium. The insoluble component in the medium is called the dispersed phase.

Q.29. What is an aqueous solution?

A solution in which water is the solvent.

Q.30. Why do we use warm water and not hot water during the preparation of a colloidal of egg albumin?

The protein in egg albumin coagulates to form a lump in hot water.