(b) Mass of urea, mv=6g Molar mass of urea, Mv=60gmol−1 Moles of urea, nv=6∕60=0.1‌mol Mass of X,mX=10g As solutions are isotonic, so ‌πU=πx ‌CURT=CXRT Assuming volume of solvent to be same in both cases, nv‌=nX 0.1‌=nx‌‌‌ where, ‌mx=‌ mass of ‌X ‌
mX
MX
‌=0.1‌‌‌ where, ‌Mx=‌ Molar mass of ‌X MX‌=‌