5 g of NaOH (molar mass 40 g/mol) is dissolved in 450 mL solution. The molarity is closest to
A{'text': '0.125 M', 'label': 'A'}
B{'text': '0.278 M', 'label': 'B'}
C{'text': '0.400 M', 'label': 'C'}
D{'text': '0.500 M', 'label': 'D'}
Answer & Solution
Correct answer: B. {'text': '0.278 M', 'label': 'B'}
1. Moles of NaOH = 5 / 40 = 0.125 mol.
2. Volume of solution = 450 / 1000 = 0.450 L.
3. Molarity = moles / volume = 0.125 / 0.450 = 0.278 mol/L.
4. So the solution is 0.278 M.
_Source: NCERT Class 12 Chemistry, Unit 1 "Solutions", Example 1.2_
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