Extra Questions For Class 9 Science Chapter 2 Is Matter Around Us Pure

Extra Questions For Class 9 Science Chapter 2 Is Matter Around Us Pure

Very Short Answer Type Questions (One Mark Each)

Q.1. Suggest separation techniques one would need to employ to separate the mixtures :
(a) Mercury and water
(b) Potassium Chloride and ammonium chloride.

Answer Ans. (a) Using separating funnel.
(b) Using sublimation.

Q.2 Salt can be recovered from solution by evaporation. Suggest some other for the same.

Answer Ans. By crystallisation and distillation.

Q.3. Name the first scientist who used the term element.

Answer Ans. Robert Boyle (1661).

Q.4. Name a metal which is liquid.

Answer Ans. Mercury is the only metal that is liquid at room temperature.

Q.5. Metals make a ringing sound when hit. What is this property known as ?

Answer Ans. Sonorous.

Q.6. Are soft drinks mixtures or pure compounds ?

Answer Ans. Soft drinks are mixtures.

Q.7. Give the constituents of soda water.

Answer Ans. Sugar, water and carbon dioxide are the constituents of soda water.

Q.8. Do constituents of a mixture retain their characteristic properties ? Say Yes’ or ‘no’?

Answer Ans. Yes.

Q.9. Is solution homogeneous or heterogeneous in nature ?

Answer Ans. Solution is a homogeneous mixture.

Q.10. Give one example of a solid solution.

Answer Ans. Brass. It is homogeneous mixture of approximately 70% copper and 30% zine.

Q.11. Give two examples of homogeneous mixtures.

Answer Ans. Salt in water, sugar in water, copper sulphate solution in water or potassium permanganate solution.

Q.12. Give two examples of heterogeneous mixtures.

Answer Ans. Mixtures of sodium chloride and iron filings, oil and water and salt and sulphur.

Q.13. Give two examples of a colloidal solution.

Answer Ans. Milk, ink, gum, smoke, blood.

Q.14. What method will you use to separate the components of a sodium chloride solution ?

Answer Ans. Evaporation.

Q.15. Name the process used by milkman to separate cream from milk.

Answer Ans. Centrifugation.

Q.16. You are given a mixture of camphor and salt. Which method you will use to separate the components of this mixture ?

Answer Ans. Sublimation

Q.17. Can we separate a mixture of camphor and naphthalene by sublimation ? Support your answer with reason.

Answer Ans. No. Because both the components undergo sublimation.

Q.18. Sulphuric acid is added to water. Will you get a mixture or a compound?

Answer Ans. We will get a mixture because its components may be in any proportion.

Q.19. In the process of chromatography, an ink drop splits up into three spots on filter paper strip. What do you conclude from this observation ?

Answer Ans. It indicates that dye in the ink drop consists of three different components.

Q.20. Lighting of a bulb in your room is a physical or chemical change ?

Answer Ans. It is a physical change.

Q.21. Can physical and chemical changes occur simultaneously. Comment.

Answer Ans. Yes. Burning of a candle involves both physical and chemical changes.

Q.22. State one difference between pure and impure substances.

Answer Ans. Pure substances contain only one type of particles while impure substances contain more than one type of particles.

Q.23. Identify solute and solvent in 80% solution of ethyl alcohol with water.

Answer Ans. Ethyl alcohol (80%) – solvent
Water (20%) – solute.

Q.24. Select the substances from the following which do not have the property of sublimation :
Camphor, potassium permanganate, copper sulphate, naphthalene.

Answer Ans. Potassium permanganate and copper sulphate do not have the property of sublimation.

Q.25. Name the technique to separate oil from water and also the principle involved in their separation.

Answer Ans. A separating funnel is used to achieve the separation. Principle : Immiscible liquids form separate layers in the mixture.

Q.26. What is the advantage of fractional distillation over simple distillation ?

Answer Ans. Fractional distillation can be used even when the boiling points of components are close to one another.

Q.27. The wool being knitted into a sweater is a physical change. Justify the statement.

Answer Ans. The sweater can be deknitted to obtain wool with no change in property.

Q.28. Classify brass and diamond as element and mixture.

Answer Ans. Brass – Mixture. Diamond – Element.

Q.29. Identify non-metals from the following elements : Carbon, potassium, silicon, chlorine, mercury.

Answer Ans. Carbon and silicon are non-metals.

Q.30. Why does the solution of sodium chloride not show Tyndall effect whereas the mixture of water and milk shows ?

Answer Ans. Sodium chloride forms a true solution in water and the particle size of sodium chloride is small and does not scatter light. Milk and water form a colloidal solution. A colloidal solution scatters light and shows Tyndall effect.

Q.31. Give two examples from daily life where Tyndall effect is observed.

Answer Ans. (i) When sunlight passes through the canopy of a dense forest.
(ii) When a fine beam of light enters a room through a small hole.

Q.32. Classify the following into element or compound :
(a) Carbon
(b) Carbon monoxide.

Answer Ans. (a) Carbon – Element
(b) Carbon monoxide – Compound

Q.33. Name a non-metal which (a) is lustrous (b) exists as a liquid at room temperature.

Answer Ans. (a) Iodine
(b) Bromine


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