Question

How many grams of NaOH are needed to make 100 ml. of a 0.5 M solution of NaOH? (Atomic weight: Na = 23, 0 + 16, H + 1)
1. 2
2. 20
3. 4
4. 1

Answer 1

Correct Answer - Option 1 : 2

The correct answer is 2.

• 2 grams of NaOH are needed to make 100 ml. of a 0.5 M solution of NaOH.
  Here, molarity is 0.5
  So, number of moles = 0.5*100 / 1000 = 0.05
  No. of moles = Mass / Molar mass
  So, mass of NaOH = 0.05*40 = 2 grams.