7th class

When ice is heated, it changes to water and water on further heating gets converted to steam. What happens when steam is condensed?

• A new substance is formed

• No new substance is formed

• Gaseous phase changes to liquid phase

• Both (b) and (c) are correct

Tags

NGSS.MS-PS1-4

The shipping industry has to bear huge financial loss because of rusting of ships. The rusting of ships occur because:

• the body of ship is always in contact with water.

• the air around the ship is humid.

• presence of salts in sea water speed up the process of rusting.

• All of the above

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Expansion on heating and contraction on cooling of metals is a:

• chemical change

• Physical change

• irreversible change

• None of these

Tags

NGSS.MS-PS1-4

Which of the following changes is accompanied by sound?

• Photosynthesis

• Spoilage of food

• Explosion of fire works

• None of these

Which of the following statements is correct?

• Evaporation is a chemical change

• Digestion of food is a chemical change

• Burning of paper is a physical change

• All of the above

Tags

NGSS.MS-PS1-2

Which of the following statements is correct?

• When coal is burnt no new substance is produced

• Rust is not formed in the absence of air or oxygen

• The fizz that comes out when a soda bottle is opened is due to a chemical change.

• Respiration is a physical process

Tags

NGSS.MS-PS1-2

Which of the following statements is correct?

• Cutting of wood into pieces is a chemical change.

• Conversion of manure from leaves is a physical change.

• Iron pipes coated with zinc do not rust easily.

• All of the above

Tags

NGSS.MS-PS1-2

Which of the following is the name of the process of obtaining salt by evaporation of sea water?

• Amalgamation

• Sublimation

• Crystallization

• Galvanization

Read the following two statements carefully and choose the correct options.

(i) Cutting of wood is considered as a chemical change

(ii) Crystallization is a physical change

• Statement (i) is correct while statement (ii) is incorrect

• Statement (ii) is correct while statement (i) is incorrect.

• Both statements are correct

• Both statements are incorrect

Tags

NGSS.MS-PS1-2

Which of the following is not a chemical change?

• Digestion of food

• Conversion of liquified petroleum gas into gas on opening the cylinder.

• Photosynthesis

• Production of biogas from animal waste

Tags

NGSS.MS-PS1-2