Changes Around Us

Which Of The Following Changes Can Be Reversed?

• Burning of a candle.

• Making biogas from cow dung.

• Drying of wet cloth.

• Baking cake in an oven.

Consider The Following Sentences And Choose The Reversible Changes

• Changing of bread into toast.

• Chemical change.

• Melting of wax.

• None of the above

An Iron Ring Is Heated. Which Of The Following Statement About It Is Incorrect?

• The ring expands

• The ring almost comes to the same size on cooling

• The change in this case is reversed

• The ring changes its shape and the change cannot be reversed

Payal Is Writing Some Sentences About Changes. Choose The Statement Where You Can Say That The Statements Is Incorrect About Changes:

• The increase in size on heating is called expansion.

• The iron rims are fitted around wooden wheel by the process of expansion.The decrease in size of an object on cooling is called contraction.

• The decrease in size of an object on cooling is called contraction.

• On cooling the hot ring of spade (blade) expands and becomes little smaller in size.

What is irreversible change ?

• A change which cannot be reversed

• A change which can be reversed

• both

• none of these

To obtain salt which of these methods is used ?

• Condensation

• Precipitation

• Evaporation

• Transpiration

On heating a substance it _______

• Expands

• Contracts

• Breaks

• Freezes

A change differs by it's

• Shape

• All of these

• Colour

• Size

Melting of ice is a

• irreversible

• Reversible

• Chemical Change

• None of these

Which Of The Following Changes Cannot Be Reversed?

• Blowing of a balloon.

• Folding a paper to make a toy Aeroplane.

• Rolling a ball of dough to make roti.

• Baking cake in an oven.