Question

What is 1) Tautomerism 2)Metamerism. and fzromerism

Answer 1

You have to take NCERT and know all the things which is inside it

Answer 2

1)
Tautomers are isomers of a compound which differ only in the position of the protons and electrons. The carbon skeleton of the compound is unchanged. A reaction which involves simple proton transfer in an intramolecular fashion is called a tautomerism.
2)
Compounds having the same molecular formula but different number of carbon atoms ( alkyl groups) on either side of functional group ( i.e., -O-,-S-, -NH-, -C(=O)-) are called metamers and the phenomenon is called metamerism.

I dont know about the last one(3). It's strange word.I think you have typed incorrectly.