explain whether 0.4 X 10^-5 is written in scientific notation

Question

A. No because the exponent is negative.

B. No because the exponent is not an integer.

C. No because 0.4 is not between 1 and 10.

Answer 1

the number to the LEFT of the decimal must be a digit from 1 to 9. it cannot be zero.

Choice C is the answer