Question

what is the composition of cell membrane

Answer 1

plasma membrane are a phospholipids , have plp structure having two protein layers at two surfaces and lipid molecules in between. 
general width is about 75-80 angstrong  

Answer 2

Cell membrane is composed of a lipid bilayer, with a polar head towards the outer side, and hydrophobic tails towards the inner side. Proteins and carbohydrates are also present in the cell membrane.Hope you got the answer.