Question detail

Case 12 ratio-step. A balanced equation is used in a calculation. Which interpretation is safest? Focus on unknown concentration when reacting volumes are known in Concentrations in mol/dm3 and titration calculations, not on a neighbouring Unit 4.3 idea.

Try the question, check the answer, then read the explanation to understand the curriculum point.

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At a glance

MCQ

Type

practice

Style

Topic

Using concentrations of solutions in mol/dm3 (chemistry only) (HT only)

Question

A. Case 12 ratio-step: Use coefficients as mole-ratio information, not formula subscripts for unknown concentration when reacting volumes are known
B. Case 12 ratio-step: Treat subscripts inside a formula as reacting mole ratios (Concentrations in mol/dm3 and titration calculations)
C. Case 12 ratio-step: Assume every reactant and product always has a 1 to 1 ratio (unknown concentration when reacting volumes are known)
D. Case 12 ratio-step: Use the largest mass as the limiting amount without mole comparison (Using concentrations of solutions in mol/dm3 (chemistry only) (HT only))

Answer

The correct option is Case 12 ratio-step: Use coefficients as mole-ratio information, not formula subscripts for unknown concentration when reacting volumes are known.

Explanation

The correct option is Case 12 ratio-step: Use coefficients as mole-ratio information, not formula subscripts for unknown concentration when reacting volumes are known. It supports the approved learning objective by keeping the method tied to unknown concentration when reacting volumes are known in Concentrations in mol/dm3 and titration calculations. The other options are incorrect because they either use the wrong quantitative relationship, lose the required unit, confuse coefficients with subscripts, or report an answer without a complete worked method.

Common mistake

Incorrect Use of Volume Units

Students often forget to convert volumes from cm3 to dm3 when calculating concentration in mol/dm3.

Always convert cm3 to dm3 by dividing the volume in cm3 by 1000 before using it in concentration calculations.

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For Concentrations in mol/dm3 and titration calculations, which answer check answer best supports this Unit 4.3 objective: (chemistry only) (HT only) Calculate an unknown concentration when reacting volumes are known and one concentration is known?