Question detail

Case 49 unit-check. A student checks the units in a calculation. Which decision keeps the method valid? Focus on atom economy measure the amount starting materials 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 49 unit-check: Keep the required unit linked to the quantity being calculated for atom economy measure the amount starting materials
B. Case 49 unit-check: Ignore the unit because the number is more important (Atom economy)
C. Case 49 unit-check: Swap dm3 and cm3 without converting the value (atom economy measure the amount starting materials)
D. Case 49 unit-check: Use grams, moles, and percentage signs interchangeably (Yield and atom economy of chemical reactions (chemistry only))

Answer

The correct option is Case 49 unit-check: Keep the required unit linked to the quantity being calculated for atom economy measure the amount starting materials.

Explanation

The correct option is Case 49 unit-check: Keep the required unit linked to the quantity being calculated for atom economy measure the amount starting materials. It supports the approved learning objective by keeping the method tied to atom economy measure the amount starting materials 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 Atom Economy with Percentage Yield

Students often confuse atom economy with percentage yield, thinking they are the same concept.

Remind students that atom economy measures how much of the starting materials become useful products, while percentage yield compares the actual product obtained to the theoretical maximum. 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) Define atom economy as a measure of the amount of starting materials that end up as useful products?