Question

assume that you take a measurement with a metric ruler that is divided into individual millimeters. which measurement has the correct number of significant figures?
a 21 mm
b 21.0 mm
c 21.00 mm
d none of the above

Explanation:

Step1: Understand significant figures

When using a metric ruler divided into individual millimeters, we can estimate to the tenths - place.

Step2: Analyze option a

21 mm has 2 significant figures. But we can be more precise.

Step3: Analyze option b

21.0 mm has 3 significant figures. The zero is significant as it is a measured digit (estimated to the tenths - place on the ruler).

Step4: Analyze option c

21.00 mm implies a precision that is not achievable with a ruler divided into individual millimeters. We can only estimate to the tenths - place, not the hundredths - place.

Step5: Analyze option d

Since option b is correct, this is incorrect.

Answer:

B. 21.0 mm