the radius of a hydrogen atom is 0.0000000529177 of a millimeter. express this number as approximation

To approximate the radius of a hydrogen atom, which is given as \( 0.0000000529177 \) millimeters, we can round this number to a simpler form.

Looking at the options:

1. 0.0000000053 is too small.
2. 0.0000006 is too large.
3. 0.00000005 is slightly smaller but not rounded correctly.
4. 0.0000005 is a reasonable approximation.

Since \( 0.0000000529177 \) rounds to \( 0.00000005 \) (considering just one significant figure after the leading zeros), the closest approximation we have in the given options is:

C. 0.00000005.