CBSE Class 10 Science Objective Type Questions & Answers

21 The chemical reaction between Hydrogen sulphide and iodine to give Hydrogen iodide and sulphur is given below: The reducing and oxidizing agents involved in this redox reaction are:

A Hydrogen sulphide and sulphur

B Sulphur and iodine respectively

C Iodine and hydrogen sulphide respectively

D Iodine and sulphur respectively

View Answer

Answer: Iodine and hydrogen sulphide respectively

22 The neutralization reaction between an acid and a base is a type of:

A Decomposition reaction

B Displacement reaction

C Addition reaction

D Double displacement reaction

View Answer

Answer: Double displacement reaction

23 The displacement reaction between iron (III) oxide and a metal X is used for welding the rail tracks. Here X is:

A Sodium pellets

B Aluminium dust

C Copper granules

D Magnesium ribbon

View Answer

Answer: Aluminium dust

24 Which of the following gases is used in the storage of fat and oil containing foods for a long time?

A Nitrogen gas

B Neon gas

C Oxygen gas

D None of these

View Answer

Answer: Nitrogen gas

25 When ferrous sulphate is heated strongly it undergoes decomposition to form ferric oxide as a main product accompanied by a change in colour from:

A Green to brown.

B Green to yellow.

C Green to blue.

D Blue to green.

View Answer

Answer: Green to brown.

26 Rusting of iron involves a chemical reaction which is a combination of:

A Oxidation as well as combination reactions

B Oxidation as well as displacement reactions

C Reduction as well as combination reactions

D Reduction as well as displacement reactions

View Answer

Answer: Oxidation as well as combination reactions

27 It is necessary to balance a chemical equation in order to satisfy the law of:

A Conservation of mass

B Conservation of energy

C Conservation of motion

D Conservation of momentum

View Answer

Answer: Conservation of mass

28 One of the following processes does not involve a chemical reaction. That is:

A Melting of candle wax when heated

B Ripening of banana

C Burning of candle wax when heated

D Digestion of food in our stomach

View Answer

Answer: Melting of candle wax when heated

29 Copper sulphate crystals when heated strongly, lose their water of crystallization to give anhydrous copper sulphate accompanied by a change in color from:

A Blue to white

B Blue to grey

C Blue to green

D Blue to sky blue

View Answer

Answer: Blue to white

30 Which one of the following salts will dissolve in water to form an alkaline solution?

A Potassium carbonate

B Potassium sulphate

C Sodium chloride

D Sodium carbonate

View Answer

Answer: Potassium carbonate

31 Bleaching powder is used as a disinfectant for water to:

A Make water germ-free

B Make water clear

C Make water tastier

D Remove all the dirt from water

View Answer

Answer: Make water germ-free

32 In the following reaction, identify the salt formed NH4OH (aq) + H2SO4 (aq) → _____ + 2H2O (l)

A NH4NO3

B (NH4)2SO4

C (NH4)2S

D (NH4)3PO4

View Answer

Answer: (NH4)2SO4

33 An ant’s sting can be treated with …………which will neutralise the effect of the chemical injected by the ant’s sting into our skin. Choose the correct option from the following to be filled in the blank space:

A Baking soda

B Caustic soda

C Methanoic acid

D formic acid

View Answer

Answer: Baking soda

34 Dilute acid does not produce carbon dioxide on being treated with:

A Lime

B Limestone

C Marble

D Baking soda

View Answer

Answer: Lime

35 Zinc granules on treating with an acid X, form the zinc sulphate (ZnSO4) salt along with the evolution of a gas Y which burns with a pop sound when brought near to a burning candle. Identify the acid X and gas evolved Y.

A X- Hydrochloric acid and Y- Hydrogen gas

B X- Sulphuric acid and Y- Hydrogen gas

C X- Sulphuric acid and Y- Oxygen gas

D X- Hydrochloric acid and Y- Oxygen gas

View Answer