Question detail

Case 45 unit-check. A student checks the units in a calculation. Which decision keeps the method valid? Focus on amount moles gas volume room temperature and in Gas volumes and amount of substance, 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

Use of amount of substance in relation to volumes of gases (chemistry only) (HT only)

Question

A. Case 45 unit-check: Keep the required unit linked to the quantity being calculated for amount moles gas volume room temperature and
B. Case 45 unit-check: Ignore the unit because the number is more important (Gas volumes and amount of substance)
C. Case 45 unit-check: Swap dm3 and cm3 without converting the value (amount moles gas volume room temperature and)
D. Case 45 unit-check: Use grams, moles, and percentage signs interchangeably (Use of amount of substance in relation to volumes of gases (chemistry only) (HT only))

Answer

The correct option is Case 45 unit-check: Keep the required unit linked to the quantity being calculated for amount moles gas volume room temperature and.

Explanation

The correct option is Case 45 unit-check: Keep the required unit linked to the quantity being calculated for amount moles gas volume room temperature and. It supports the approved learning objective by keeping the method tied to amount moles gas volume room temperature and in Gas volumes and amount of substance. 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 Volume and Moles

Students often confuse the volume of a gas with the amount in moles, forgetting that they need to use the relationship that 1 mole of gas occupies 24 dm3 at room temperature and pressure.

To fix this, remember to use the formula: moles = volume / 24 dm3 when calculating the amount in moles from gas volume.

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For Gas volumes and amount of substance, which option best supports this Unit 4.3 objective: (chemistry only) (HT only) Calculate amount in moles from gas volume at room temperature and pressure?