100ml of ethanol with density =0.78cc is made up to a litre with pure water .calculate the molality?

Density is not measured in cc. Your question is garbled. You have to be pretty sharp in this business to do the work at all. Spelling mistrakes kill people. Clean up your act.

Let's assume you meant "density = 0.78". Then 100 ml masses 78 grams. That means the concentration of a solute in a solution in terms of amount of substance in a specified amount of mass of the solvent. This contrasts with the definition of molarity which is based on a specified volume of solution. (from wikipedia.org)

So you have 900 grams of water and 78 grams of ethanol. Molality = 78/900 = 0.08666...