The units on the ruler are inches, centimeters, and millimeters. Nanometers (nm) is equivalent to 10^-9 m. Each graduation on the ruler represents 0.1 millimeters or 0.01 centimeters. The other side also has a graduation of 0.1 inch. The function of the ruler depends on how you use it.
Explanation: All gases are diatomic i.e they are covalently bonded to another atom of the same element in order to attain stability. O atom is usually unstable because of it's incompletely filled outermost shell.
