Answer
See below.
Work Step by Step
Apply the SI prefixes.
a. 0.2866 m.
b. 0.000085 V.
c. 0.76 g. (assuming the final zero is not significant)
The correct number of significant digits is unclear when you write out the number.
d. 0.0000000000621 s
e. 0.0000000225 m
f. 2500000000 V.
The correct number of significant digits is unclear when you write out the number.