NCERT Class X Science Class: Chapter –1. Chemical Reactions and Equations – Part-3

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Question 11:

Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is

Answer: B

Image the decomposition reaction

Image the Decomposition Reaction

Image the decomposition reaction

Question 12:

Which of the following is/are an endothermic processes?

  1. Dilution of sulphuric acid

  2. Sublimation of dry ice

  3. Condensation of water vapours

  4. Evaporation of water

  5. (i) and (iii)

  6. (ii) only

  7. (iii) only

  8. (ii) and (iv)

Answer: D

Image the endothermic reaction

Image the Endothermic Reaction

Image the endothermic reaction

Question 13:

In the double displacement reaction between aqueous potassium iodide and aqueous lead nitrate, a yellow precipitate of lead iodide is formed. While performing the activity if lead nitrate is not available, which of the following can be used in place of lead nitrate?

  1. Lead sulphate (insoluble)

  2. Lead acetate

  3. Ammonium nitrate

  4. Potassium sulphate

Answer: B

Lead sulphate being insoluble will not dissociate into ions.

Lead sulphate dissociate in lead ions

Lead Sulphate Dissociate in Lead Ions

Lead sulphate dissociate in lead ions

Question 14:

Which of the following gases can be used for storage of fresh sample of an oil for a long time?

  1. Carbon dioxide or oxygen

  2. Nitrogen or oxygen

  3. Carbon dioxide or helium

  4. Helium or nitrogen

Answer: D

Question 15:

The following reaction is used for the preparation of oxygen gas in the laboratory

Which of the following statements is/are correct about the reaction?

  1. It is a decomposition reaction and endothermic in nature

  2. It is a combination reaction

  3. It is a decomposition reaction and accompanied by release of heat

  4. It is a photochemical decomposition reaction and exothermic in nature

Answer: A

Question 16:

Which one of the following processes involve chemical reactions?

  1. Storing of oxygen gas under pressure in a gas cylinder

  2. Liquefaction of air

  3. Keeping petrol in a china dish in the open

  4. Heating copper wire in presence of air at high temperature

Answer: D

Image heating coppe air at high temperature

Image Heating Coppe Air at High Temperature

Image heating coppe air at high temperature