Question

in 3,4,4,5-Tetramethylheptane what is the importance of tetra and why can it not be written without 'Tetra'?

Answer 1

Tetra means 4, which implies that there are 4 methyl in the above compound. If you don't write tetra before methyl then the name could be misleading or confusing. Therefore in order to remove these kind of situation IUPAC has included the rule to write, di, tri, tera, penta, etc. before the substituent if it is repeated several times in the same compound.