What are the possible changes in a chemical reaction?
Evolution of gas
Change in Colour
Formation of Precipitate
Chemical reactions could evolve a gas, the colour could change and precipitates could be formed.
The products could be in a different state from the reactants too.
The identity of an element depends on the number of protons in it. In a chemical reactions, electrons are transferered or shared. A new element cannot be formed in a chemical reaction.