i am not able to understand the solution. please help.

sir if we keep W=1000g then we get w/m x M/W as the molality of the solution. But my question is that won't the value of M=18 affect the equation in anyway? What is the role of M exactly?

The normality of 10ml of a '20V' H2O2 solution is

Sir in last 2 questions you practiced in video lecture of osmotic pressure u took volume of solution in kg but you told earlier that volume of solution while calculating molarity should be in litres . Why did you used kg instead of lit ?