Atomic Number And Mass Number Of Sodium Are 11 And 23 Respectively

The atomic number and the mass number of sodium are 11 and 23 respectively. What information is conveyed by this statement.

Answers:

Atomic number = 11; No of protons = 11
Mass number = 23 = Number of protons + Number of neutrons.
No of neutrons = 23-11 = 12.