NCERT Class VI Science Solutions: Chapter 6 – Changes around Us Part 2

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Question 7:

Iron rim is made slightly smaller than the wooden wheel. The rim is usually heated before fixing into the wooden wheel, because on heating the iron rim

  1. Expands and fits onto the wooden wheel.

  2. Contracts and fits onto the wooden wheel.

  3. No change in the size takes place.

  4. Expands first, then on cooling contracts and fits onto the wooden wheel.

Answer: D

VERY SHORT ANSWER QUESTIONS

Question 8:

Look at Fig, which shows three situation

  1. A burning candle

  2. An extinguished candle

  3. Melting wax.

Result for A reversible change

A Reversible Change

Result for A reversible change

Which of these shows a reversible change and why?

Answer:

Melting of wax in (c), which on cooling changes back to solid wax.

Question 9:

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

Answer:

The changes that can be reversed (reversible).

Question 10:

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?

Answer:

Expansion of metal cap on heating.

SHORT ANSWER QUESTIONS

Question 11:

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

  1. Water into water vapour.

  2. Water vapour into water.

  3. Ice into water.

  4. Curd into milk.

Answer:

  1. Yes, condensation

  2. Yes, evaporation

  3. Yes, freezing

  4. Not possible