volcanic eruption
Most chemical changes happen between molecules, so they are unseen.
Cytoplasm
In a Chemistry Lab because of some of the ongoing experiments gas leakage might happen that pollutes the air . Also some of biological experiments might pollute the environment.
A fire is a chemical change due to the irreversible changes that happen.
Cooking involves chemical changes.
Heating can be due to a chemical change, for example burning a fuel is in effect a chemical reaction with oxygen. Also some chemical reactions are exothermic, ie they produce heat. Not so many produce cooling, but one is the combination of ice and salt.However heating and cooling happen for other reasons as well, so you can't say they are examples of chemical changes. It is correct to say that some chemical changes result in heating and cooling.
The majority of these changes are recognized.
something
gets bigger and changes color
Something must change in the internal or external environment of the organism. This change can be physical or chemical and will result in a response from the organism. The scientific name for these changes are stimuli (singular = stimulus), examples of which are touching a hot surface, being scared, exercising and drugs. Hope this helps
It begins to boil.
magnesium sulphate