Chirkut.বাংলা

MCQ practice · SSC Chemistry Board questions · Chapter 6: Concept of Mole and Chemical Counting

Chattogram Board 2025

If 20 g of NaOH is dissolved in 0.5 liter of solution, what is the concentration of that solution?

Think it through first, then pick an option.

  1. a 0.1 M
  2. b 0.5 M
  3. c 1.0 M
  4. d 2.0 M
Answer and explanation

Correct answer: c 1.0 M

Moles = 20/40 = 0.5; S = 0.5/0.5 = 1.0 M.

Why the other options are wrong

  • a 0.1 M: 0.1 M would need only 2 g in 0.5 liter; here it is 1.0 M.
  • b 0.5 M: 0.5 is the number of moles (20/40), not divided by the volume; 0.5/0.5 = 1.0 M.
  • d 2.0 M: 2.0 M would need 40 g in 0.5 liter; here there is 20 g, 1.0 M.