Which of the following statements are correct?
(A) The electronic configuration of Cr is [Ar] 3d$$^5$$4s$$^1$$.
(B) The magnetic quantum number may have a negative value.
(C) In the ground state of an atom, the orbitals are filled in order of their increasing energy order.
(D) The total number of nodes are given by n - 2.
Choose the most appropriate answer from the options given below.

Let us evaluate each statement:

(A) The electronic configuration of Cr is [Ar] 3d$$^5$$4s$$^1$$.

This is correct. Chromium has an exceptional configuration due to the extra stability of a half-filled 3d subshell.

(B) The magnetic quantum number may have a negative value.

This is correct. The magnetic quantum number $$m_l$$ ranges from $$-l$$ to $$+l$$, so it can take negative values.

(C) In the ground state of an atom, the orbitals are filled in order of their increasing energy order.

This is correct. This is the Aufbau principle, which states that electrons fill orbitals starting from the lowest energy level.

(D) The total number of nodes are given by n - 2.

This is incorrect. The total number of nodes (radial + angular) is given by $$n - 1$$, not $$n - 2$$.

Therefore, statements (A), (B), and (C) are correct.

Hence, the correct answer is Option D ((A), (B) & (C) only).