CBSE – 9th Standard Science


Class 9 Question Bank Chapter 2 – Is matter around us pure

Q1. What is mixture?

Ans. Which contains more than one substance is called Mixture.

Q2.  What are the examples of mixture?

Ans. Sea water, minerals, soil etc

Q3. What do you mean by homogeneous mixture?

Ans. Mixture which has a uniform composition throughout. Such mixtures are called homogeneous mixtures or solutions.

Q4. What do you mean by heterogeneous mixture?

Ans. Mixtures, which contain physically distinct parts and have non-uniform compositions. Such mixtures are called heterogeneous mixtures.

Q5. What is a solution?

Ans. A solution is a homogeneous mixture of two or more substances.

Q6. What does solution consist of?

Ans. A solution has a solvent and a solute as its components.

Q7. What do you mean by solvent?

Ans. The component of the solution that dissolves the other component in it is called the solvent.

Q8. What do you mean by solute?

Ans. The component of the solution that is dissolved in the solvent is called the solute.

Q9. What do you mean by Saturated solution?

Ans. when no more solute can be dissolved in a solution at a given temperature, it is called a saturated solution.

Q10. What do you mean by Unsaturated solution?

Ans. If the amount of solute contained in a solution is less than the saturation level, it is called an unsaturated solution.

Q11. What is Solubility?

Ans. If the amount of the solute contained in the Saturated solution at a particular temperature is called its solubility.

Q12. How to calculate the Concentration of Solution?

Ans. The concentration of a solution is the amount of solute present in a given amount (mass or volume) of solution, or the amount of solute dissolved in a given mass or volume of solvent.

Q13. What do you mean by Alloys?

Ans. Alloys are mixture of two or more metals or non metals.

Q14. Can Alloys be separated?

Ans. Alloys cannot be separated into their components by physical method.

Q15. What is a Suspension?

Ans. A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium.

Q16. How Heterogeneous mixture can be separated?

Ans. Heterogeneous mixtures can be separated into their respective constituents by simple

physical methods like handpicking, sieving, filtration.

Q17. Why Distillation is used?

Ans.  It is used for the separation of components of a mixture containing two miscible liquids that boil without decomposition and have sufficient difference in their boiling points.

Q18. What is Crystallization?

Ans. Crystallization is a process that separates a pure solid in the form of its crystals from a solution.

Q19. What are the types of pure substances?

Ans. On the basis of substance’s chemical composition, can be classified either as elements or compounds.

Q20. What is an Element ?

Ans. Element is a basic form of matter that cannot be broken down into simpler substances by chemical reactions.

Q21. What is a Compound ?

Ans. A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.

Try these:-

How will you separate a mixture containing kerosene and petrol

(difference in their boiling points is more than 25ºC), which are

miscible with each other?

 Name the technique to separate

(i) butter from curd,

(ii) salt from sea-water,

(iii) camphor from salt.

What type of mixtures are separated by the technique of crystallisation?

A solution contains 40 g of common salt in 320 g of water.

Calculate the concentration in terms of mass by mass percentage of the solution

Classify the following into elements, compounds and mixtures.

(a) Sodium

(b) Soil

(c) Sugar solution

(d) Silver

(e) Calcium carbonate

(f) Tin

(g) Silicon