UP Board Class 9 Science Chapter 2 Is Matter Around Us Pure Multiple Choice Questions

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Is Matter Around Us Pure Multiple Choice Questions

Question 1. Which of the following is a pure substance?

  1. Air
  2. Distilled water
  3. Steel
  4. Brass

Answer: 2. Distilled water

Any substance that contains only one type of particle (for example., molecules/atoms etc.) is said to be a pure substance. Among the given options, distilled water has only one type of particle (i.e. H2O molecules) while air is a mixture of various gases, steel and brass are alloys.

∴ Hence (2) is the correct option.

Up Board Class 9 Science Notes For Chapter 2 Is Matter Around Us Pure Multiple Choice Questions

Question 2. Which of the following properties does not prove that water is a compound?

  1. The ratio of hydrogen and oxygen by mass in water is fixed
  2. Water has a fixed boiling point (b.p.)
  3. Simple physical methods cannot separate the constituents of water
  4. Distilled water and tap water have the same taste and constituents

Answer: 4. Distilled water and tap water have the same taste and constituents

  • Distilled water and tap water have different tastes and different constituents.
  • Distilled water has pure H2O molecules while tap water may contain other molecules also.
  • The ratio of hydrogen and oxygen by mass remains 1:8 in all the H2O molecules.
  • They have fixed b.p. and cannot be separated into their constituents by simple physical methods.

∴  (4) is the correct option.

Question 3. Two elements X and Y combine to give a product Z. The correct statement about Z is

  1. Z has more mass than that of X
  2. Z has less mass than that of X
  3. Z has less mass than that of Y
  4. Z show the same properties as of X and Y

Answer: 1. Z has more mass than that of X

Product Z is formed by the combination of X and Y, thus has more mass than of X and Y separatly. Also Z is entirely a new product, thus cannot show same properties, as of X and Y

Question 4. During the purification of water, which of the following step(s) is incorrect?

  1. Sedimentation of water
  2. Loading of water with alum
  3. Electrolysis of water
  4. Chlorination of water

Answer: 3. Electrolysis of water

  1. During the purification of water
  2. Sedimentation is done to remove suspended particles (for example., solids).
  3. Loading with alum is done to remove small particles like clay present in colloidal state.
  4. Electrolysis is not done, as it dissociates the water molecules in H2(g) and O2(g).
  5. Chlorination is done to kill the bacteria’s (e.g use of bleaching powder).

Hence, (3) is the correct option.

Question 5. The pair of substance (s) that can be separated by sublimation is/are

  1. NH4Cl and salt
  2. sugar solution in water
  3. salt solution in water
  4. kerosene oil and water

Answer: 1. NH4Cl and salt

A mixture of ammonium chloride and salt can be separated by sublimation as NH4Cl changes to vapour directly, i.e. without changing in liquid state while salt does not.

Hence, (1) is the correct option.

Question 6. To prepare iron-sulphide by heating a mixture of iron filings and sulphur powder, we commonly use

  1. Petri-dish
  2. Water-glass
  3. China-dish
  4. Beaker

Answer: 3. China-dish

We commonly use Chinese for heating because it can bear high temperatures on heating the mixture.

Question 7. Which of the following substances cannot be broken down by a chemical method?

  1. Ammonia (NH3)
  2. Helium (He)
  3. Methane (CH4)
  4. Water (H2O)

Answer: 2. Helium (He)

Helium cannot be broken down by a chemical method as it is an element, while other substances are compounds and can dissociate in their constituents because ammonia is made by two elements nitrogen and hydrogen, methane is made by carbon and hydrogen and water is made by hydrogen and oxygen.

Question 8. Smoke and fog differ from each other because

  1. They have different dispersion medium
  2. They have different dispersed phase
  3. Both (1) and (2)
  4. None of these

Answer: 2. They have different dispersed phase

Smoke and fog both have the same dispersion medium but they differ in dispersed phase. In smoke, the dispersed phase is solid while in fog, the dispersed phase is liquid.

Hence, (2) is the correct option.

Question 9. Which of the following will not show the Tyndall effect?

  1. Smoke
  2. Foam
  3. Jelly
  4. Salt solution

Answer: 4. Salt solution

The salt solution will not show the Tyndall effect as it is a true solution and particles of salt solution are very small (size < 1 nm). So, these cannot scatter a beam of light and, hence do not show the Tyndall effect.

Question 10. Which of the following is an example of emulsion?

  1. Mist
  2. Milk
  3. Face cream
  4. Both (2) and (3)

Answer: 4. Both (2) and (3)

Milk and face cream, both are emulsions of liquid in liquid. Mist is an aerosol, present in our atmosphere. Hence, is the correct option.

Question 11. Which of the following is a physical change?

  1. Rusting of iron
  2. Formation of water vapours from water
  3. Cooking of food
  4. Formation of water from hydrogen and oxygen

Answer: 2. Formation of water vapours from water

Formation of water-vapours from water is a physical change, as we can get back the water by simple physical method (i.e. condensation) while all others are examples of chemical changes because products formed can not give back the former reactant (i.e. substance) by physical methods.

Hence, (2) is the correct option.

Question 12. The correct statement about an article made up of iron getting rusted, is/are

  1. The process is called corrosion and is a physical change
  2. The process is called dissolution and is a physical change
  3. The process is called corrosion and is a chemical change
  4. The process is called dissolution and is a chemical change

Answer: 3. The process is called corrosion and is a chemical change

The rusting of an article made up of iron is called corrosion. Corrosion is a chemical change because rust is a chemical compound (product) which has different properties and formula than that of reactants.

∴ \(4 \mathrm{Fe}+3 \mathrm{O}_2+x \cdot \mathrm{H}_2 \mathrm{O} \longrightarrow \underbrace{2 \mathrm{Fe}_2 \mathrm{O}_3 \cdot x \cdot \mathrm{H}_2 \mathrm{O}}_{\text {Rust }}\)

Hence, (3) is the correct option.

Question 13. Which of the following is considered to be a pure substance?

  1. Sodium chloride
  2. Muddy water
  3. Granite
  4. Milk of magnesia

Answer: 1. Sodium chloride

Question 14. What is the sulphur?

  1. A metal
  2. A metalloid
  3. A non-metal
  4. None of these

Answer: 3. A non-metal

Question 15. Which of the following elements is a non-metal?

  1. Fe
  2. Na
  3. Cu
  4. Cl

Answer: 4. Cl

Question 16. Which one of the following is a metalloid?

  1. Na
  2. Fe
  3. Cu
  4. As

Answer: 4. As

Question 17. In which of the following the constituents are present in any ratio?

  1. Compound
  2. Mixture
  3. Colloid
  4. Solution

Answer: 4. Solution

Question 18. Which of the following is an example of a homogeneous substance?

  1. Polluted air
  2. Muddy water
  3. Salt solution
  4. None of the above

Answer: 3. Salt solution

Question 19. Which of the following is not an example of a colloidal solution?

  1. Glue
  2. Milk
  3. Salt solution
  4. Blood

Answer: 4. Blood

Question 20. Which one of the following statements is suitable (correct) for the mixture of sulphur and carbon disulphide?

  1. Heterogeneous mixture and represent Tyndall effect
  2. Homogeneous mixture and represent Tyndall effect
  3. Heterogeneous mixture but does not show the Tyndall effect
  4. Homogeneous mixture but does not show the Tyndall effect

Answer: 4. Homogeneous mixture but does not show Tyndall effect

Is Matter Around Us Pure Fill In The Blanks

Question 1. A colloid is a mixture and its components can be separated by the technique known as
Answer: Heterogeneous, centrifugation

Question 2. Ice, water and water vapour look different and display different properties, but they are the same.
Answer: Physical, chemically

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