Question

the
Explain
occurrence
example
the different conditions required for
of chemical changes along with the example. ICSE class 9 ​

Answer 1

Answer:

Close contact- For a chemical reaction to take place the reactants should be brought in close contact i.e., they should be mixed.

Sodium + Water → Sodium hydroxide + Water

Solution form- Some substances react with each other only when they are mixed in the solution form, e.g.,

(aq.)

Silvernitrate

+

(aq.)

Sodiumchloride

→

(ppt.)

Silvernitrate

+

(aq.)

Sodiumnitrate

Heat-Some reactants need to be heated to undergo a chemical change, e.g.,

Potassium chlorate

⟶

heat

Potassium chloride + Oxygen

Light - Some reactions take place in the presence of light.

Carbon dioxide + Water

chlorophyll

sunlight

Glucose + Oxygen

Answer 2

Answer:

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