Which is an example of a chemical change?

a. frying an egg
b. boiling water
c. melting butter
d. chopping onions

Answer : The correct option is (a).

Explanation :

Physical change : It is a change in which no new compounds are formed only changes occurs in size or state of substance. In this, there is no changes in the substance or compound.Chemical change : It is a change in which a new compounds are formed by the chemical reaction. Changes occurs in their chemical composition and properties.

Frying an egg  : A new substance is form by the heating. So, it is a chemical change.

Boiling water  : Only changes in state. So, it is a physical change.

Melting butter  : Only changes in state. So, it is a physical change.

Chopping onions  : Only changes in the size of the substance. So, it is physical change.

Frying an egg is a chemical change. it cannot go back to its original form. 

Hope the image of the frequency formula

You would be correct, boiling water does disinfect contamination.    the property of disinfecting means to kill  germs, bacteria and other pathogens or contamination  that might cause an infection or cause a person to become sickly. a couple methods of disinfecting are using soap, other cleaning supplies or by simply "boiling" the contaminate.  the reason why boiling water disinfects certain attributes is because some cells cannot survive the heat and pressure.