Each type of hydrogen meansthose hydrogens which
are equivalent due to symmetry or internal
rotations. They have on average the same chemical environment.
A good way to test
for equivalent hydrogens is to replace them by a test atomeg. Cl
1-chloro-2-methylpropene3-chloro-2-methylpropene
If the name is the
same no matter which H is replaced then the H atoms are equivalent