How many alkene isomers are possible for compound with molecular formula `C_(5)H_(10)`?

How many isomers are possible for the compound with molecular formula C_(4)H_(8) ?

How many isomers are possible for a compound of molecular formula C_4H_10 ?

How many isomers are possible for an alkane with molecular formula C_(4)H_(10) ?

How many structural isomers are possible for the molecular formula C_(5)H_(11) Br ?

What is the total number of structural isomers possible for a compound with the molecular formula C_(5)H_(10) ?