5. An average human hair is approximately 90,000 nm thick. How many cm is that? (1 cm = 1x10^7 nm) • 9 x 1011 cm
• 9 x 1012 cm
• 9,000 cm
• 0.009 cm

0.009 cm

Explanation:

When using a calculator its mostly common sense. One human hair is obviously not 9,000 cm thick, and 9x10^11 or 9x10^12 is way more than 9,000 so it would be 0.009

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.