Final answer:
Measurement with a ruler with the smallest divisions of 0.1 cm justifies two significant figures; one certain digit and one estimated digit after the decimal, reflecting the precision of the measuring tool.
Step-by-step explanation:
When measuring with a device that has the smallest divisions of 0.1 cm, the number of significant figures justified is two. The whole number part (digit to the left of the decimal point) is known with certainty, which in this case is either 9 or 10. The second significant figure is the digit in the tenths place, which can be estimated when the measurement falls between the smallest divisions on the ruler. Since the ruler does not allow for the hundredths place to be estimated (there are no smaller markings), we cannot justify a third significant figure.
In the example of measuring an object to be between 9 and 10 centimeters, we would write our measurement as 9.1 cm, 9.2 cm, etc. The '9' is the certain digit, and the digit after the decimal is the estimated digit, therefore providing two significant figures. No further precision is justified due to the limitation of the ruler.