The atomic number of an element is 11 and its mass number is 23. The correct order representing the number of electrons, protons and neutrons respectively in this atom is :

The element with the atomic number $\text{Z}=11$  and mass number $\text{A}=23$  is sodium (Na). In neutral atom number of protons is equal to number of electrons. Hence, Na contains total 11 electrons in different shells.

Number of neutrons in sodim atom is $n=\text{A}-\text{Z}$

So, that  $n=23-11=12$

Therefore, the correct answer is option A.