Question detail

Case 14 unit-check. A student checks the units in a calculation. Which decision keeps the method valid? 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 14 unit-check: Keep the required unit linked to the quantity being calculated for ratios fractions and percentages atom-economy calculations
B. Case 14 unit-check: Ignore the unit because the number is more important (Atom economy)
C. Case 14 unit-check: Swap dm3 and cm3 without converting the value (ratios fractions and percentages atom-economy calculations)
D. Case 14 unit-check: Use grams, moles, and percentage signs interchangeably (Yield and atom economy of chemical reactions (chemistry only))

Answer

The correct option is Case 14 unit-check: Keep the required unit linked to the quantity being calculated for ratios fractions and percentages atom-economy calculations.

Explanation

The correct option is Case 14 unit-check: Keep the required unit linked to the quantity being calculated 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)?