Final answer:
The number 0.707 mL has three significant figures, including the first '7', the '0', and the second '7'.
Step-by-step explanation:
The number of significant figures in the measured number 0.707 mL is three. Significant figures are the digits that carry meaning contributing to its precision. This includes all the non-zero numbers, any zeros between them, and any trailing zeros in a decimal. In our number 0.707 mL, the first '7' is significant because it's the first non-zero digit, the '0' is significant because it is between significant figures, and the second '7' is significant because it is a non-zero digit. Leading zeros, such as those in a number like 0.006606 s, are not significant.