Final answer:
The length of a piece of double-stranded DNA with 100 base pairs is 34 nm.
Step-by-step explanation:
The length of a double-stranded DNA with 100 base pairs can be calculated by multiplying the number of base pairs by the distance between each base pair.
In this case, each base pair is separated by a distance of 0.34 nm. Therefore, the length of the DNA would be 100 base pairs * 0.34 nm = 34 nm.