PHYSICAL AND CHEMICAL CHANGES

Which Of The Following Is A Physical Change?

• Rusting of iron

• Combustion of magnesium ribbon

• Burning of candle

• Melting of wax

Which Of The Following Sentences Is Or Are Correct?

• Rusting is a chemical change because a new substance is formed

• Beating of Aluminum metal to make Aluminum foil, is a physical change

• Digestion of food is a chemical change

• All the above

Paheli’s Mother Made A Concentrated Sugar Syrup By Dissolving Sugar In Hot Water. On Cooling, Crystal Of Sugar Got Separated. This Indicates a :

• Physical change that can be reversed

• Chemical change that can be reversed

• Physical change that cannot be reversed

• Chemical change that cannot be reversed

A Chemical Change May Involve:

• Change in colour only

• Change in temperature only

• Evolution of gas only

• All of these

• Only evolution of gas

Magnesium + Oxygen ---->

• Magnesium oxide

• Magnesium bicarbonate

• Magnesium ribbon

• Magnesium dioxide

Both oxygen and water are essential for rusting.

• TRUE

• FALSE

Calcium hydroxide + Carbon dioxide ---->

• Calcium carbonate

• water

• both of these

• none of these

Baking soda is ______________

• 1.calcium hydroxide

• 2.sodium bicarbonate

• 3.sodium hydrogen carbonate

• 4.Both 2&3

The quantity of moisture in costal areas is quite low as compared to deserts

• TRUE

• FALSE

Iron pillar near the Qutub Minar in Delhi is famous for the following facts. Which of these facts is responsible for its long stability?

• It is more than 7 metres high

• It weighs about 6000 kg

• It was built more than 1600 years ago

• It has not rusted after such a long period