Question detail
Which conversion should be used before substituting 25.0 cm3 into a mol dm-3 concentration calculation?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Mathematical requirements and assessment objectives
Question
- A. A. 25.0 cm3 = 0.0250 dm3, because cm3 values are divided by 1000.
- B. B. 25.0 cm3 = 25 000 dm3, because cm3 values are multiplied by 1000.
- C. C. 25.0 cm3 = 2.50 dm3, because the decimal point moves one place.
- D. D. 25.0 cm3 = 0.250 dm3, because only one significant figure is needed.
Answer
A. 25.0 cm3 = 0.0250 dm3, because cm3 values are divided by 1000.
Explanation
Handling data and units correctly means converting volume into the unit required by the equation. Concentration in mol dm-3 uses dm3, so 25.0 cm3 must be divided by 1000 to give 0.0250 dm3. Keeping three significant figures preserves the precision of the original measurement. This directly supports the learning objective to handle data, units, standard form, significant figures and uncertainty because the answer explains the mathematical decision and the reporting convention.
Common mistake
Significant Figures Confusion
Students often round numbers incorrectly when performing calculations, leading to an inaccurate number of significant figures.
To fix this, students should identify the significant figures in the original data and ensure that their final answer reflects the correct number of significant figures based on the least precise measurement.
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