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Some Basic Concepts of Chemistry · Class 11 · CBSE · Science Chemistry

What is the concentration of a solution in molality (m) if 4 text{ g} of NaOH is dissolved in 500 text{ g} of water? (Molar mass of NaOH = 40 text{ g…

Practice question from Some Basic Concepts of Chemistry (Class 11 · CBSE · Science Chemistry), with the correct answer and a step-by-step solution.

easy · MCQ · Q-467B93

What is the concentration of a solution in molality (mm) if 4 g4 \text{ g} of NaOH is dissolved in 500 g500 \text{ g} of water? (Molar mass of NaOH=40 g mol−1NaOH = 40 \text{ g mol}^{-1})

  1. A.0.1 m0.1 \text{ m}
  2. B.0.2 m0.2 \text{ m}Correct answer
  3. C.0.4 m0.4 \text{ m}
  4. D.0.08 m0.08 \text{ m}

Solution

Moles of NaOH=4/40=0.1 molNaOH = 4 / 40 = 0.1 \text{ mol}. Mass of solvent (water) =500 g=0.5 kg= 500 \text{ g} = 0.5 \text{ kg}. Molality (m)=Moles of solute/Mass of solvent in kg=0.1/0.5=0.2 mol kg−1(m) = \text{Moles of solute} / \text{Mass of solvent in kg} = 0.1 / 0.5 = 0.2 \text{ mol kg}^{-1} or 0.2 m0.2 \text{ m}.

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