Difference between reversible and irreversible changes
A thick coating of a paste of Plaster of Paris (POP) is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured bone immobilized. Can the change in POP be reversed?
Dissolving sugar in water is an example of ?
- is irreversible
- is reversible
- involves the formation of a new substance
- occurs slowly
Change of a bud into a flower is a change which cannot be reversed. Give four more such example.
Which of the following changes cannot be reversed?
(a) Hardening of cement
(b) Freezing of ice cream
(c) Opening a door
(d) Melting of chocolate
Paheli mixed flour and water and made dough, rolled the dough to make chapati, baked the chapati on a pan, dried the chapati and ground it in a grinder to make powder. Identify the changes as the changes that can be reversed or that cannot be reversed?
Why does Aluminium metal items which shines like silver when new, turns dull gray after sometime?
Chemicals of dish washing brings about a change
Dirt sticks quickly to Al metal surface
None of the choice
Protective layer of Al2O3 forms on metal surface
2. State whether this change can be reversed or not.
(f) Making biogas from cow dung.
Three substances given below are kept in the open for a few days and some changes were observed.
Which of the substances will show a chemical change?
Both eggs & moth balls
All eggs, plastic bottle and moth balls
- Cutting of trees
- Melting of ghee
- Burning of candle
Blooming of a flower
When baking soda is mixed with lemon juice, bubbles are formed. Which gas is evolved in this reaction?
Differentiate between a reversible and an irreversible change
Name the different types of changes. [1 MARK]
In an exam, a teacher asked students to give an example of a change which is a physical as well as a chemical change? Which one of the following examples is correct?
Burning of candle
Beating of aluminium to make foil
Dissolving salt in water
please give me a good answer for my question
clay is moulded into different shapes it is soft .when it is baked it is hard. Is it a chemical change or a physical change? How?
It was Paheli's birthday. Her grandmother gave her two gifts made up of metals, one old dull silver spoon and a pair of lustrous gold ear-rings she was surprised to see the difference in the appearance of the two metals. Can you explain the reason for this difference ?
This gas is not a constituent of air.
Change of milk to curd is a _______ [desirable/undesirable] change.
Differentiate between physical and chemical change.
(B) Classify the following as physical or chemical change.
(vi) Knotting a rope
(I) New substance is formed.
(II) The change is reversible
(III) The change is permanent
- Only (I) and (II)
- (I), (II) and (III)
- Only (I)
- Only (I) and (III)
Melting of ice, ageing of living beings, stretching of a rubber band, dissolution of sugar in water
Nitrogen gas is the most abundantly available gas in the atmosphere.