Question

Permanent change is:
(A) Physical change
(B) Chemical change
(C) Both physical and chemical change
(D) None of the above

Answer 1

Hint: The change is not reversible in nature. A simple example of such a change is souring of milk or digestion of food. The resulting substances have different properties because of the new arrangement of atoms and molecules of the starting material with the change.
Complete step by step answer:
- Permanent changes are also called chemical changes.
- In a chemical change or a chemical reaction, the substances which undergo reaction are called reactants or starting material and the new substances produced with different properties are called products.
- Some chemical reactions emit heat as a form of energy, those are called exothermic reactions.
- The reactions which absorb heat during a chemical change are called endothermic reactions.
> Basic evidence of a chemical change-
1) Change in colour
2) Change in smell
> Change in both physical and chemical properties of a substance
- Physical change is accompanied by the change of state of the substance.
Example – melting of ice
-A chemical change occurs in our everyday life.
In another way, it may be categorised into-
> Change of organic compounds
This includes the burning of natural gas, ripening of fruits.
> Change of inorganic compounds
This includes steel formation, fireworks lightning, photosynthesis.
> Types of chemical reactions are –
A) Combination
B) Decomposition
C) Single displacement
D) Double displacement
E) Combustion
F) Redox
So, the correct option is B.

Note: Chemical reactions are generally irreversible. But there are exceptions. At equilibrium that is when the product and reactant concentrations are the same, the chemical reaction is reversible in nature.
Example: $$\text{ammonium chloride }\rightleftharpoons \text{ ammonia + hydrogen chloride}$$
The symbol $$\rightleftharpoons$$denotes that the reaction is reversible.