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NDA 2024 GAT · General Knowledge · Mole Concept and States of Matter · hard

4 g of NaOH (molar mass 40 g/mol) is dissolved in water to make 500 mL of solution. The molarity of the solution is

Single correct option

4 g of NaOH (molar mass 40 g/mol) is dissolved in water to make 500 mL of solution. The molarity of the solution is
  1. A. 0.1 M
  2. B. 0.2 M
  3. C. 0.8 M
  4. D. 2 M
Show answer and solution

Answer: (B) 0.2 M

Moles of NaOH = 4/40 = 0.1 mol. Volume = 0.5 L, so molarity = 0.1/0.5 = 0.2 M. The trap is 0.1 M, which uses the number of moles without converting the volume, and 0.8 M, which comes from dividing 4 by 5 incorrectly. The volume must be in litres.
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Original question written in the NDA 2024 GAT pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake