Changes Around Us: Class 6 Science Q&A · Page 2
30 free answers on Changes Around Us (Science) for Class 6 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- ScienceClass 6CBSE
Can we reverse the following changes? If yes, suggest the name of the method. (a) Water into water vapour (b) Water vapour into water (c) Ice into water Curd into milk.
Water into water vapour – Yes, by using the method of condensation, water vapour can be converted to water. Water vapour into water – Yes, by using the evaporation method, water can be converted to water vapour. Ice into water – Yes, by freezing method, water can be converted to Curd into milk – No, it is an irreversible
- ScienceClass 6CBSE
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?
On immersing the metal cap in hot water, it expands in size hence it can be removed easily.
- ScienceClass 6CBSE
A piece of iron is heated till it becomes red-hot. It then becomes soft and is beaten to a desired shape. What kinds of changes are observed in this process-reversible or irreversible?
It is a reversible change when a piece of iron on heating can be beaten into desired shape. Since the object of desired shape can be again heated and beaten back to give its original shape.
- ScienceClass 6CBSE
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 (a) expands and fits onto the wooden wheel (b) contracts and fits onto the wooden wheel (c) no change in the size takes place expands first, then on cooling contracts and fits onto the wooden wheel.
Solution: : expands first, then on cooling contracts and fits onto the wooden Iron expands on heating. So the smaller iron rim expands on heating fits into the wooden wheel and on cooling it contracts to fit into the wooden wheel tightly. Hence it does not come out.
- ScienceClass 6CBSE
Rolling of chapati and baking of chapati are the changes that (a) can be reversed (b) cannot be reversed (c) can be reversed and cannot be reversed, respectively cannot be reversed and can be reversed, respectively
: can be reversed and cannot be reversed, Once the chapati is baked it cannot be reversed. But rolling of chapati is a physical reversible change because there is no change in the properties of kneaded flour.
- ScienceClass 6CBSE
Salt can be separated from its solution (salt dissolved in water), because (a) mixing of salt in water is a change that can be reversed by heating and melting of salt (b) mixing of salt in water is a change that cannot be reversed (c) mixing of salt in water is a permanent change mixing of salt in water is a change that can be reversed by evaporation
Solution: (d): mixing of salt in water is a change that can be reversed by evaporation. Salt can be separated from water solution by evaporating the water. Hence mixing of salt in water is a reversible change.
- ScienceClass 6CBSE
While lighting a candle, Paheli observed the following changes. (i) Wax was melting (ii) Candle was burning (iii) Size of the candle was reducing (iv) Melted wax was getting solidified Of the above, the changes that can be reversed are (a) (i) and (ii) (b) (ii) and (iii) (c) (iii) and (iv) (i) and (iv)
Solution: (d): Wax was melting; Melted wax was getting solidified Solid wax can be melted and melted wax gets solidifies again. Hence melting of wax and its solidification are reversible changes.
- ScienceClass 6CBSE
1. An iron ring is heated. Which of the following statement about it is incorrect? (a) The ring expands. (b) The ring almost comes to the same size on cooling. (c) The change in this case is reversed. The ring changes its shape and the change cannot be reversed.
Solution: (d): The ring changes its shape and the change cannot be reversed. The change is reversible in case of iron ring. Since the ring expands on heating and comes back to its original size on cooling.
- ScienceClass 6CBSE
Which of the following change cannot be reversed? (a) Hardening of cement (b) Freezing of ice cream (c) Opening a door Melting of chocolate
Solution: : Hardening of cement Hardening of cement is cannot be reversed because once hardened it cannot come back to its original shape.
- ScienceClass 6CBSE
Pick the change that can be reversed from the following. (a) Cutting of trees (b) Melting of ghee (c) Burning of candle Blooming of flower
: Melting of ghee The melted ghee can be frozen again hence this change can be reversed. Cutting of trees, burning of candle and blooming of flower cannot be reversed.