Question

Pooja took a candle in a vessel and heated the vessel. Even though the candle did not burn,
it changed its shape and state. What kind of change is this?
A. naturalization
B. physical change
C. chemical change
D. none of these

Answer 1

Hint:We will determine the change in chemical composition and physical state of the candle during the heating. If chemical composition is changing, the change is chemical . If only the physical state is changing, the change is physical.

Complete step-by-step answer :The reaction of an acid with a base is known as naturalization. The product of naturalization is salt. Salts are neutral so the reaction is known as naturalization.

When a change in temperature or pressure causes a change in the form such as the shape or state of
a chemical compound, the change is known as physical change.

When a change in temperature, pressure or a reaction with another chemical cause a change in the
chemical composition of the compound, the change is known as chemical change.

The candle is made up of wax. Pooja took a candle in a vessel and heated the vessel. On heating, the vessel becomes hot and transfers the heat to the candle. Even though the candle did not burn, but it melts which causes a change in its shape and state. On cooling, the wax gets solidified so only the shape and the state is changing, so it is a physical change.

Therefore, option (B) physical change, is correct.

Note:In physical, only physical state change whereas the chemical composition remains the same. In a chemical change, mainly the chemical composition changes. The physical state can remain the
same or changed during a chemical change. The burning of methane in air produces carbon dioxide and water. This change is a chemical change because new chemical compounds are produced by the reaction.