Question

What is 0.000000685 written in scientific notation?

685×10−9685×10^−9

68.5×10−868.5×10^−8

6.85×10−86.85×10^−8

6.85×10^−7

Answer 1

all of the last are exponents

Answer 2

I would say D but am not sure.
I calculated the zeros after the decimal point and then it would make sense because the answer of 6.85x10^-7 matches the original expression