How to find R n S isomers

How many positional isomer of n-Decene will show geometerical isomerism

Identify compound (A) How many isomers including geometrical isomers are possible for (A) ?

How many isomers are possible for heptane(excluding optical isomers)

How many isomers are possible for butane?

How many isomers are possible for hexane?

How many isomers are possible for nitrophenol ?

How many isomers are possible for pentane?

How many isomers for the following molecule

If S be the sum P the product and R be the sum of the reciprocals of n terms of a GP then p^(2) is equal to S/R b.R/S c.(R/S)^(n) d.(S/R)^(n)