The diameter of a hydrogen atom is about 5 x 10^-11 meters. Suppose 8.4 x 10^5
hydrogen atoms were arranged side by side in a straight line. Multiply these numbers to find the length of this line of atoms. What is the length in scientific notation?

0.000042 meters
42 x 10^-6 meters
4.2 x 10^-6 meters
4.2 x 10^-5 meters