Secondary School (English Medium) (5 to 8) कक्षा ६ - CBSE Question Bank Solutions

While lighting a candle, Paheli observed the following changes.

1. Wax was melting
2. Candle was burning
3. Size of the candle was reducing
4. Melted wax was getting solidified.

Of the above, the changes that can be reversed are

Salt can be separated from its solution (salt dissolved in water), because ______.

Rolling of chapati and baking of chapati are the changes that ______.

Look at the figure which shows three situations.

A piece of iron is heated till it becomes red-hot. it then becomes soft and is beaten to a desired shape. What kind of changes are observed in this process-reversible or irreversible?

Paheli had bought a new bottle of pickle from the market. She tried to open the metal cap to taste it but could not do so. She then took a bowl of hot water and immersed the upper end of the bottle in it for five minutes. She could easily open the bottle now. Can you give the reason for this?

Can we reverse the following change? If yes, suggest the name of the method.

Water into water vapour

Can we reverse the following change? If yes, suggest the name of the method.

Water vapour into water

Can we reverse the following change? If yes, suggest the name of the method.

Ice into water

Can we reverse the following change? If yes, suggest the name of the method.

Curd into milk

Which of the following changes cannot be reversed?

1. Blowing of a balloon
2. Folding paper to make a toy aeroplane
3. Rolling a ball of dough to make roti
4. Baking cake in an oven
5. Drying a wet cloth
6. Making biogas from cow dung
7. Burning of a candle

Boojho’s sister broke a white dove, a symbol of peace, made of Plaster of Paris (POP). Boojho tried to reconstruct the toy by making a powder of the broken pieces and then making a paste by mixing water. Will he be successful in his effort? Justify your answer.

Tearing of paper is said to be a change that cannot be reversed. What about paper recycling?

Give one example of change which occurs on heating but can be reversed.

Give one example of change which occurs on heating but cannot be reversed.

Give one example of change which occurs on cooling but can be reversed.

Give one example of change occurs on mixing two substances, but can be reversed.

Give one example of change which occurs on mixing two substances, but cannot be reversed.

A potter working on his wheel shaped a lump of clay into a pot. He then baked the pot in an oven. Do these two acts lead to the same kind of changes or different? Give your opinion and justify your answer.

Conversion of ice into water and water into ice is an example of change which can be reversed. Give four more examples where you can say that the changes can be reversed.