Question

Which of the following is a chemical change?
a. Melting of ice
b. Rusting of iron
c. Changing of water into ice
d. Dissolving of common salt into water​

Answer 1

Answer: Option (b)

Rusting of iron is an example of Chemical change.

Explanation:

• Chemical change is a process in which material reacts with other substance to form new substance.

• These chemical changes are also known as "Chemical reactions".

• The rusting of iron is a process in which the iron is exposed to environment.

• In this expotion, the iron reacts with Oxygen and form oxide.

• In chemical reactions, some chemical reactions release heat which are called as Exothermic reaction.

• Some chemical reactions absorb heat which are known as Endothermic reactions.

• Other examples of chemical change are digestion of food, formation of curd etc.

Answer 2

$\huge\mathfrak\green{Heyaa!!!}$

$\huge\mathfrak\red{Answer:-}$

☆what is a chemical change?

☆A chemical change is a process where a substance undergoes a change in its chemical structure.

☆It is a permanent change.

☆It is not reversible.

☆Which of the following is a chemical change?

a. Melting of ice

b. Rusting of iron

c. Changing of water into ice

d. Dissolving of common salt into water

☆Here option b is correct answer.

♤Explanation:

☆Formula of rusting of iron: Fe2O3

Fe + H2O + O2 => Fe(OH)3 => Fe2O3.nH2O

☆It is a chemical change because two substances react together and form a new substance. 

☆When iron rusts, iron molecules react with oxygen molecules to make a compound called iron oxide.

☆It would have been a  a physical change if iron molecules remained pure iron throughout the process.

☆Rust cannot be converted back to iron by any process. Hence irreversible.