Answer:
D 0.00009
Explanation:
9 × 10^-5 = 9 × 1/10^5 = 9 × 1/100,000
= 9 × 0.00001
= 0.00009
_____
Comment on place value
The exponent of 10 associated with the place value in a decimal number increases from 0 to the left of the decimal point, and decreases from -1 to the right of the decimal point:
100. = 10²
10. = 10¹
1. = 10⁰
0.1 = 10⁻¹
0.01 = 10⁻²
0.001 = 10⁻³
0.0001 = 10⁻⁴
0.00001 = 10⁻⁵
This simple realization can help you immensely with scientific notation.