Assertion and Reason Questions for Class 9 Science Chapter 2 Is Matter Around Us Pure

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Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.

Q.1. Assertion : When a beam of light is passed through a colloidal solution placed in a dark place the path of the beam becomes visible.
Reason : Light gets scattered by the colloidal particles.

Answer Answer: (a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
Light is scattered by colloidal particles, making the path of the beam visible.

Q.2. Assertion : A mixture of benzoic acid and naphthalene can be separated by crystallization from water.
Reason : Benzoic acid is soluble in hot water but naphthalene is insoluble in hot water.

Answer Answer: (a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
Benzoic acid is soluble in hot water but naphthalene is not soluble, hence separation can be carried out by Chap 2 : Is Matter Around us Pure http://www.cbse.online Download all GUIDE and Sample Paper pdfs from http://www.cbse.online or http://www.rava.org.in Page 16 hot water crystallisation.

Q.3. Assertion : A solution of table salt in a glass of water is homogeneous.
Reason : A solution having different composition throughout is homogeneous.

Answer Answer: (c) Assertion (A) is true but reason (R) is false.
A solution having same composition throughout is homogeneous.

Q.4. Assertion : A mixture of sugar and benzoic acid can be separated by shaking with ether.
Reason : Sugar is insoluble in water.

Answer Answer: (c) Assertion (A) is true but reason (R) is false.
Sugar is soluble in water and insoluble in ether.

Q.5. Assertion : In sublimation, a substance changes directly from solid to vapour without passing through
liquid state and vice-versa.
Reason : Distillation involves two processes i.e., vaporisation and condensation.

Answer Answer: (b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
Both are definitions of sublimation and distillation respectively.

Q.6. Assertion : True solution exhibits Tyndall effect.
Reason : Particles are very large in size.

Answer Answer: (d) Assertion (A) is false but reason (R) is true.
True solutions do not exhibit Tyndall effect since the particle size is very small to scatter light.

Q.7. Assertion : Colloidal solutions are stable and the colloidal particles do not settle down.
Reason : Brownian movement counters the force of gravity acting on colloidal particles.

Answer Answer: (a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
Due to constant movement of particles colloidal particles do not settle down.

Q.8. Assertion : A solution of table salt in a glass of water is homogeneous.
Reason : A solution having different composition throughout is homogeneous.

Answer Answer: (c) Assertion (A) is true but reason (R) is false.
A solution having same composition throughout is homogeneous.

Q.9. Assertion : Impure benzoic acid can be purified by sublimation.
Reason : Benzoic acid sublimes on heating.

Answer Answer: (a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
Benzoic acid sublimes on heating while impurities do not.

Q.10. Assertion : Tyndall effect is an optical property.
Reason : Electrophoresis is an electrical property.

Answer Answer: (b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
Scattering of light by colloidal particles is an optical activity. Coagulation of colloidal particles under an electrical field is an electrical property.

Q.11. Assertion : A mixture of acetone and methanol can be separated by fractional distillation.
Reason : The difference between their boiling points is very less.

Answer Answer: (a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
Whenever the difference in boiling points of two liquids is less than 25cC they are separated by fractional distillation.

Q.12. Assertion : Chloroform and benzene form a pair of miscible liquids and they are separated by fractional
distillation.
Reason : Boiling point of benzene is less than that of chloroform.

Answer Answer: (c) Assertion (A) is true but reason (R) is false.
Chloroform (b.pt. 60cC) and benzene (b.pt. 80c) can be separated by fractional distillation since fractional distillation is used for the separation of two or more liquids with difference in their boiling points of less than 25cC.

Q.13. Assertion : A mixture of camphor and ammonium chloride cannot be separated by sublimation.
Reason : Camphor on heating sublimes, ammonium chloride does not.

Answer Answer: (c) Assertion (A) is true but reason (R) is false.
Both camphor and ammonium chloride sublime on heating.

Q.14. Assertion : A mixture of glucose and m-dinitrobenzene can be separated by shaking it with ether.
Reason : Glucose is soluble in water.

Answer Answer: (b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).

Q.15. Assertion : Hot water is used for separation of benzoic acid from naphthalene.
Reason : Whenever a crystal is formed it tends to leave out the impurities.

Answer Answer: (b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
Benzoic acid dissolves in hot water but naphthalene does not therefore, hot water is used for separation of benzoic acid from naphthalene.

3 thoughts on “Assertion and Reason Questions for Class 9 Science Chapter 2 Is Matter Around Us Pure

  1. Thank you 💓 it was useful for my public exam preparation

    1. thank you so much

      .

      .

  2. thanks a lot

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