Answer : The correct option is, (C) a compound being separated into two elements
Explanation :
Chemical change : It is a change where changes occurs in the chemical composition and thus resulting in the formation of new compound or substance. It is an irreversible reaction.
The indication of chemical changes are :
Formation of gas bubbles.
Formation of precipitate.
Change in color.
Change in temperature.
Change in volume.
Change in smell or taste.
Evolution of heat, light and sound.
Physical change : It is a change in which shape and size of a substance changes. In this there is no change in the chemical composition of the substance and no new substance is forming. It is a reversible reaction.
The mixtures are physical combinations.
The indication of chemical changes are :
Change in shape.
Change in form.
Change in size.
Change in phase.
As per question, the option A, B and C is a physical change and option C is a chemical change.
Option C is a chemical change because when a compound being separated into two elements then their chemical compositions are changes and thus resulting in the formation of new compound or substance.
Hence, the option C represents a chemical change.