Discussion Forum



1)

5.0 g of sodium hydroxide(molar mass 40 g $mol^{-1}$ ) is dissolved in little quantity of water and the solution is diluted up to  100mL. what is the molarity of the resulting solution?


A) 0.1 mol d$m^{-3}$

B) 1.0 mol d$m^{-3}$

C) 0.125 mol d$m^{-3}$

D) 1.25 mol d$m^{-3}$

Answer:

Option D

Explanation:

 Given, W (mass of solute) =5.0 g

 m (molar mass of solute)=40 g mol-1

 Volume=100 mL

 Molarity  is given as,

 M= Moles of solute/ Volume of solution (in L)

M= W x 1000/  m x volume  of solution (in mL)

  =$\frac{5.0 g \times 1000}{40 \times 100}$

 =1.25 mol d$m^{-3}$