What does the atomic number mean or represent? also how do i make someone brainliest

The atomic number refers to the number of protons in the nucleus of an atom. The identity of an element is determined by its number of protons. The atomic number uniquely identifies a chemical element. It is identical to the charge number of the nucleus.

And if you want to mark someone's answer as brainliest first you have to get more than 1 answer to your question and then there will be a message above that says “Mark as brainiest”

the answer is a and have a great day

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.