Question

"The atomic number and mass number of sodium are $11$ and $23$ respectively".What information does this statement convey?

Answer 1

The atomic number and mass number of sodium are $11$ and $23$ respectively.

This suggests that number of proton in sodium $=11$ and number of nucleons i.e. proton and neutrons in sodium $=23.$ Thus, number of neutrons $=12$ and also Since no. of protons $=$ no. of electrons $=11$

So, they are similar.