Question

An aqueous solution of NaCl is 270m. If the density of the solution is 1.20g/ml. Find a) % NaCl by mass b) Molarity of NaCl in the solution.

Answer 1

I assume you men 270 molal.
270 m means 270 mol/kg solvent.
g NaCl = 270 x 58.5 (apprx) = estimated 16000 g (you need to go through the entire problem and redo the math; I've estimated all of these numbers.
The mass of the solution is 1000 g solvent + 16000 g NaCl = about 17000g total
%NaCl = (mass NaCl/total mass)*100 = about 94%. I'll wait to do the b part until you've confirmed this post is correct.