Question

write advantage of CGS system

Answer 1

The density of water is 1 (g/cm^3). Many other liquid and solid densities are within an order of magnitude of 1. That's useful for chemists who often measure amounts by volume and wish to easily convert to mass. Also most amounts used by chemists are around the range of 1-100 in centimeters and grams. mks units are more convenient for the amounts physicists usually deal with. 

It uses a non-prefixed unit as the base unit of mass, unlike mks which uses kilograms. But it uses a prefixed unit as the base unit of distance, so it has as many disadvantages as advantages in that respect. Particularly using a non-power-of-three prefix is tricky. It requires a little bit to stop and think when you need to convert nanometers to centimeters.