Question detail

Case 87 unit-check. A student checks the units in a calculation. Which decision keeps the method valid? Focus on that balanced chemical equation the total relative in Relative formula mass, 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

Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations

Question

A. Case 87 unit-check: Keep the required unit linked to the quantity being calculated for that balanced chemical equation the total relative
B. Case 87 unit-check: Ignore the unit because the number is more important (Relative formula mass)
C. Case 87 unit-check: Swap dm3 and cm3 without converting the value (that balanced chemical equation the total relative)
D. Case 87 unit-check: Use grams, moles, and percentage signs interchangeably (Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations)

Answer

The correct option is Case 87 unit-check: Keep the required unit linked to the quantity being calculated for that balanced chemical equation the total relative.

Explanation

The correct option is Case 87 unit-check: Keep the required unit linked to the quantity being calculated for that balanced chemical equation the total relative. It supports the approved learning objective by keeping the method tied to that balanced chemical equation the total relative in Relative formula mass. 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

Misunderstanding Mass Conservation

Students often think that the mass of reactants and products can differ if gases are involved, not realizing that the total mass remains constant.

Emphasize that the law of conservation of mass states that no atoms are lost or gained, so the total mass of reactants must equal the total mass of products, regardless of the state of matter. Keep the correction anchored to Relative formula mass; check formula, substitution, calculation, final answer, and unit where relevant.

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For Relative formula mass, which unit conversion answer best supports this Unit 4.3 objective: Explain that in a balanced chemical equation the total relative formula mass of reactants in the stated quantities equals that of the products?