Question detail

Case 15 ratio-step. A balanced equation is used in a calculation. Which interpretation is safest? Focus on ratios fractions and percentages atom-economy calculations in Atom economy, 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

Yield and atom economy of chemical reactions (chemistry only)

Question

A. Case 15 ratio-step: Use coefficients as mole-ratio information, not formula subscripts for ratios fractions and percentages atom-economy calculations
B. Case 15 ratio-step: Treat subscripts inside a formula as reacting mole ratios (Atom economy)
C. Case 15 ratio-step: Assume every reactant and product always has a 1 to 1 ratio (ratios fractions and percentages atom-economy calculations)
D. Case 15 ratio-step: Use the largest mass as the limiting amount without mole comparison (Yield and atom economy of chemical reactions (chemistry only))

Answer

The correct option is Case 15 ratio-step: Use coefficients as mole-ratio information, not formula subscripts for ratios fractions and percentages atom-economy calculations.

Explanation

The correct option is Case 15 ratio-step: Use coefficients as mole-ratio information, not formula subscripts for ratios fractions and percentages atom-economy calculations. It supports the approved learning objective by keeping the method tied to ratios fractions and percentages atom-economy calculations in Atom economy. 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

Confusing Ratios with Percentages

Students often confuse how to use ratios and percentages in atom-economy calculations, leading to incorrect answers.

To fix this, students should practice converting ratios to percentages by dividing the part by the whole and multiplying by 100, ensuring they understand the difference between the two concepts. Keep the correction anchored to Atom economy; check formula, substitution, calculation, final answer, and unit where relevant.

Related flashcards

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For Atom economy, which option best supports this Unit 4.3 objective: (chemistry only) Use ratios, fractions and percentages in atom-economy calculations. (MS 1c)?