WBCS.LIVE practice 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)

Solve this multiple-choice question and check the correct answer with its explanation below.

Answer options

  1. 2
  2. 20
  3. 4
  4. 1

Correct answer and explanation

Correct answer: 2

Explanation: āœ… Correct Answer: A) 2 šŸ“š Explanation: Molarity (M) = Moles / Volume (L). Moles = Molarity Ɨ Volume = 0.5 Ɨ 0.1 = 0.05 moles. Molecular weight of NaOH is 23+16+1 = 40. Mass needed = 0.05 Ɨ 40 = 2 grams.