aditi wrote:Please help me to calculate the molarity from microgram/ml of a compound with 0.2 microgram/ml
Molarity is the number of moles of something dissolved in one liter of solvent. So first, lets work with a liter. If it is 0.2 ug/mL, then it is 0.2 mg/L.
Now we need to know what the something is and it's atomic or molecular weight. That will tell you how many grams a mole of something weighs. Since you didn't identify what the substance was, I can't do that step.