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Chemistry · PYQ NEET UG 2019(2)
हिन्दीThe density of \( 2 \) \( \mathrm{M} \) aqueous solution of \( \mathrm{NaOH} \) is \( 1.28 \) \( \mathrm{g/cm^3} \). The molality of the solution is [Given that molecular mass of \( \mathrm{NaOH} = 40 \) \( \mathrm{g\,mol^{-1}} \)]
Correct answer · Option 4
\( 1.67 \) \( \mathrm{m} \)
Explanation
Mass of \( 1 \) \( \mathrm{L} \) solution = \( 1280 \) \( \mathrm{g} \). Mass of solute = \( 2 \times 40 = 80 \) \( \mathrm{g} \). Mass of solvent = \( 1280 - 80 = 1200 \) \( \mathrm{g} \). Molality \( m = \frac{2}{1.2} = 1.67 \) \( \mathrm{m} \).
