Viva Voce: Mixture & Compound | Lab Manuals for Class 9 PDF Download

Q.1. Name the constituents of the following compounds.
Water, Sugar, Magnesium oxide, Iron sulphide.

Water – Hydrogen and Oxygen
Sugar – Carbon, Hydrogen, Oxygen
Magnesium Oxide – Magnesium and Oxygen
Iron sulphide – Iron and Sulphur

Q.2. What happens when dilute sulphuric acid is added to a compound of iron and sulphur?

The iron sulphide reacts with dilute sulphuric acid to form hydrogen sulphide gas, it is colourless gas with the smell of rotten eggs.

Q.3. How can you prove that water is a compound?

On electrolysis of water we get hydrogen and oxygen gas is separated in fixed ratio always

i. e., H : O is 2 : 1.

Q.4. Give two examples of mixture formed by compounds.

Common salt + sugar.
Smoke + methane + carbon dioxide in air.

Q.5. Give two examples of mixture formed by two or more elements.

Nitrogen and oxygen in air, copper and gold in alloy.

Q.6. Why do we use carbon disulphide as a solvent to dissolve sulphur?

As sulphur does not dissolve in water, carbon disulphide is used as a solvent.

Q.7. Classify the following into mixture and compound.
soil, air, alloy, sugar, soap solution, milk, coal, blood, glucose.

Mixture – soil, air, alloy, soap solution, milk, coal, blood Compound – sugar, glucose.

Q.8. What happens when dilute sulphuric acid is added to a mixture of iron and sulphur?

Iron reacts with dilute sulphuric acid and hydrogen gas is released.

Q.9. Why do mixtures show heterogeneous appearance?

The constituents of mixture are not mixed uniformly hence show heterogeneous appearance.

Q.10. Give two examples of non-uniform composition.

Sand and salt, sugar and salt, blood.

Q.11. Why doesn’t air show same composition over all places?

Air is a mixture but various gases, particles, pollutants keep on adding in air in various proportions.

Q.12. Is alloy a homogeneous or heterogeneous mixture?

It is a homogeneous mixture.

Q.13. Give two examples of uniform composition in mixture.

Sugar in water, salt in water.

Q.14. Give one test to show that mixtures can be separated physically.

Take sulphur + iron-mixture, roll magnet over it, iron filings clings to magnet.

Q.15. Is mixture a pure substance?

No