Changes around Us Test

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Changes around Us Test - 6

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following change cannot be reversed?

A
Hardening of cement

B
Freezing of ice cream

C
Opening a door

D
Melting of chocolate

Solution

A. Hardening of cement is an irreversible change as we cannot reverse back to the original cement powder form once the cement hardens.

B. Freezing of ice-cream is reversible change as it can be reversed back by heating and it will convert to original form.

C. Opening of a door is reversible change as it can be reversed simply by closing the door.

D. Melting of chocolate is reversible change as it can be reversed by cooling the chocolate to its original form.

Hence, option $$A$$ is the correct answer.
Question 2
1 / -0

Which of the following is true about dissolving salt in water?

A
Dissolving salt in water is an example of a reversible change

B
Dissolving salt in water is an example of a irreversible change

C
It depends on the conditions of dissolution

D
None of the above

Solution

Dissolving salt in water is an example of a reversible change. When salt is mixed with water it disappears because it dissolves in the water to make salty water. But we can get the salt back again by boiling off the water (distillation). That leaves the salt behind.
Option $$A$$ is correct.
Question 3
1 / -0

Melting of ice is a

A
reversible change

B
irreversible change

C
chemical change

D
None of these

Solution

Melting of ice is a reversible change because melted ice (i.e. water) can freeze back into ice.
Question 4
1 / -0

Which of the following is permanent change?

A
Physical change

B
Chemical change

C
Both physical and chemical change

D
None of the above

Solution

A chemical change is permanent change and new substance is formed in it.
Forms of energy, such as heat, light or electricity, may be emitted or absorbed during a chemical reaction. A chemical change is generally irreversible.

Hence option B is correct.
Question 5
1 / -0

Burning of Magnesium ribbon is a _______

A
Chemical change

B
Physical change

C
Reversible change

D
None of the above

Solution

Magnesium ribbon burns with dazzling light in air and forms magnesium oxide.
$$2Mg+O_2\rightarrow 2MgO$$.
The above change is a chemical changes as new substance is formed after change. Original
substances cannot be retrieved by simple physical processes.So it is chemical change.
Hence option A is correct.
Question 6
1 / -0

The change of water into vapour (vaporisation) is a:

A
physical and reversible change

B
chemical and reversible change

C
physical and irreversible change

D
irreversible change

Solution

Vapour is another physical state of water. Liquid water can be obtained from the condensation of vapour. Also, the vapour is chemically still water($$H_2O$$) as its chemical composition doesn't change.
Hence, the vaporisation of water is a physical and reversible change.
Question 7
1 / -0

Things or processes which cannot be reversed are called

A
Irreversible process

B
Reversible process

C
Cyclic process

D
None of the above

Solution

Things or processes which cannot be reversed are called irreversible process. Burning of coal is irreversible as it will not produce coal again.
Question 8
1 / -0

Salt can be separated from its solution (salt dissolved in water) because:

A
mixing salt in water is a change that can be reversed by filtration

B
mixing salt in water is a change that can be reversed by decantation

C
mixing of salt in water is a change that can be reversed by freezing

D
mixing of salt in water is a change that can be reversed by evaporation

Solution

Mixing salt in water is a change that can be reversed by evaporation. It is a type of reversible change in which the physical state of salt changes, from solid to aqueous, other than that its chemical composition remains the same.

Hence the water will get converted into its gaseous form(steam), leaving behind solid salt.
Question 9
1 / -0

Reversible change is:

A
formation of vapour on heating of milk

B
formation of butter from churning curd

C
ripening of fruit

D
falling of leaves from trees

Solution
Question 10
1 / -0

Stretching of a rubber band is what kind of change?

A
Irreversible change

B
physical and reversible change

C
chemical and irreversible change

D
physical and irreversible change

Solution

During stretching of the rubber band only the size of the rubber band changes. The rubber band comes back to its original shape and size, once it is released. This is a physical and reversible change.
Hence option A is correct.

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Re-Attempt Weekly Quiz Competition

Changes around Us Test - 6

Result

Changes around Us Test - 6

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SHARING IS CARING

Question 1

Hardening of cement

Freezing of ice cream

Opening a door

Melting of chocolate

Solution

Question 2

Dissolving salt in water is an example of a reversible change

Dissolving salt in water is an example of a irreversible change

It depends on the conditions of dissolution

None of the above

Solution

Question 3

reversible change

irreversible change

chemical change

None of these

Solution

Question 4

Physical change

Chemical change

Both physical and chemical change

None of the above

Solution

Question 5

Chemical change

Physical change

Reversible change

None of the above

Solution

Question 6

physical and reversible change

chemical and reversible change

physical and irreversible change

irreversible change

Solution

Question 7

Irreversible process

Reversible process

Cyclic process

None of the above

Solution

Question 8

mixing salt in water is a change that can be reversed by filtration

mixing salt in water is a change that can be reversed by decantation

mixing of salt in water is a change that can be reversed by freezing

mixing of salt in water is a change that can be reversed by evaporation

Solution

Question 9

formation of vapour on heating of milk

formation of butter from churning curd

ripening of fruit

falling of leaves from trees

Solution

Question 10

Irreversible change

physical and reversible change

chemical and irreversible change

physical and irreversible change

Solution

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