Question detail

Case 53 ratio-step. A balanced equation is used in a calculation. Which interpretation is safest? Focus on relative formula mass the sum the 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 53 ratio-step: Use coefficients as mole-ratio information, not formula subscripts for relative formula mass the sum the relative
B. Case 53 ratio-step: Treat subscripts inside a formula as reacting mole ratios (Relative formula mass)
C. Case 53 ratio-step: Assume every reactant and product always has a 1 to 1 ratio (relative formula mass the sum the relative)
D. Case 53 ratio-step: Use the largest mass as the limiting amount without mole comparison (Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations)

Answer

The correct option is Case 53 ratio-step: Use coefficients as mole-ratio information, not formula subscripts for relative formula mass the sum the relative.

Explanation

The correct option is Case 53 ratio-step: Use coefficients as mole-ratio information, not formula subscripts for relative formula mass the sum the relative. It supports the approved learning objective by keeping the method tied to relative formula mass the sum the 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

Confusing Relative Atomic Mass with Relative Formula Mass

Students often confuse relative atomic mass (Ar) with relative formula mass (Mr), thinking they are the same.

Remember that relative atomic mass refers to a single atom, while relative formula mass is the sum of the relative atomic masses of all atoms in a formula.

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For Relative formula mass, which formula choice answer best supports this Unit 4.3 objective: Define relative formula mass, Mr, as the sum of the relative atomic masses of atoms in the numbers shown in a formula?