MediumChemistryHigh School (11–12)Atoms and Molecules › Measurement, Units and Significant FiguresNumericalBoard Exam
Three students weigh three parts of a sample on three different balances: 25.341 g, 2.05 g and…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Three students weigh three parts of a sample on three different balances: , and . What total mass should they report?
Need a reminder? The key ideaShow
Non-zero digits are significant. Zeros between them are significant. Zeros at the left are not. Zeros at the right count only after a decimal point. Sums keep the fewest decimal places; products keep the fewest significant figures.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Add. .
Step 2. Decimal places. has only one decimal place, so the sum keeps one.
Step 3. Round. rounds to . The zero after the point is significant and must be written.
Answer: .
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