8 g sodium hydroxide is dissolved in 200 mL solution. Molar mass is 40 g per mole. What is the molarity?
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Answer and explanation
Correct answer: 1.0 mole per litre
Molarity is moles of solute per litre of final solution. First, moles of NaOH = mass ÷ molar mass = 8 g ÷ 40 g mol−1 = 0.20 mol. Next, 200 mL = 0.200 L. Thus, M = 0.20 ÷ 0.200 = 1.0 mol L−1, so option A is correct. The other values arise from using grams or millilitres without proper conversion.
Frequently asked questions
What is the correct answer to this question?
1.0 mole per litre
Why is this the correct answer?
Molarity is moles of solute per litre of final solution. First, moles of NaOH = mass ÷ molar mass = 8 g ÷ 40 g mol−1 = 0.20 mol. Next, 200 mL = 0.200 L. Thus, M = 0.20 ÷ 0.200 = 1.0 mol L−1, so option A is correct. The other values arise from using grams or millilitres without proper conversion.
Which subject and chapter does this question cover?
This is a Class 11 Chemistry question. Chapter: Chapter 01: Solutions.
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