Tag: classification of changes

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Multiple choice chemistry changes around us can all changes be reversed? substances and objects classification of changes

 Iron adopts changes slowly and gradually by process of :

  1. rusting

  2. moldings

  3. fermentation

  4. explosions
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Iron adopt changes slowly and gradually when it comes in contact with air (moisture, oxygen etc)
When Iron reacts with $'n'$ molecules of water in the pressure of oxygen, it forms rust. Hence the process is known as a rusting.
$4Fe+3{ O } _{ 2 }+2n{ H } _{ 2 }O\longrightarrow 2{ Fe } _{ 2 }{ O } _{ 3 }.n{ H } _{ 2 }O$
Multiple choice chemistry changes around us can all changes be reversed? substances and objects classification of changes

 Burnt sparklers and burnt books pages are examples of 

  1. reversible change

  2. irreversible change

  3. no change

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Burnt sparklers and burnt books pages are examples of irreversible changes, as they are permanent changes which cannot be undone. Once these materials are burnt in to ashes, the original materials cannot be recovered back.

Multiple choice chemistry changes around us can all changes be reversed? substances and objects classification of changes

Which of the following is not a reversible change?

  1. Heating of water to steam

  2. Cooking of egg to scrambled eggs

  3. Heating of wax to molten wax

  4. Cooling a cake
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A reversible change can be undone to return to the original state. Cooking an egg involves chemical changes that permanently alter the proteins, making it irreversible.

Multiple choice chemistry changes around us can all changes be reversed? substances and objects classification of changes

Which of the following change cannot be reversed ?

  1. Hardening of cement

  2. Freezing of ice cream

  3. Opening a door

  4. Melting of choclate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A reversible change is a physical change that can be undone. 
A final substance can be converted back to the original substance without creating any new material.
An irreversible change is a permanent change that cannot be undone.


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.
Option A is the correct answer.

Multiple choice chemistry changes around us can all changes be reversed? substances and objects classification of changes

Burnt sparklers and burnt books pages are examples of:

  1. reversible process

  2. irreversible process

  3. rusting

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Irreversible changes $-$ because when they are burnt formation of gas and ashes takes place i.e. chemical reaction is taking place and new substance are formed which can't be reversed back.


      Book pages  $\quad \xrightarrow { \text{burning} } \quad { CO } _{ 2 }+$ other substances.

Hence, the correct option is $\text{B}$

Multiple choice chemistry changes around us can all changes be reversed? substances and objects classification of changes

Which of the following changes are irreversible?

  1. Raw egg to boiled egg

  2. Woollen yarn to knitted sweater

  3. Bud to flower

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The following changes are irreversible.We cant covert product into reactant in these processes

1) Raw egg to boiled egg.
2) Woollen yarn to the knitted sweater.
3) Bud to flower.

Multiple choice chemistry changes around us can all changes be reversed? substances and objects classification of changes

Which of the following represents a reversible change?

  1. A metal rod on heating expands (its length increases).

  2. A metal rod on cooling contracts (its length decreases).

  3. Both of the above

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The following represents a reversible change. A metal rod on heating expands (its length increases). A metal rod on cooling contracts (its length decreases).