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Which of the following statements are correct? (A) The electronic configuration of Cr is [Ar] 3d5 4s1. (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 energies. (D) The total number of nodes are given by n − 2. Choose the most appropriate answer from the options given below: (1) (A), (C) and (D) only (2) (A) and (B) only (3) (A) and (C) only (4) (A), (B) and (C) only

1. (A), (C) and (D) only
2. (A) and (B) only
3. (A) and (C) only
4. (A), (B) and (C) only

Correct answer: (A), (B) and (C) only

Solution

Option (A) is correct as chromium has an unusual electron configuration due to stability reasons. Option (B) is also correct because the magnetic quantum number can take on negative values, reflecting the orientation of orbitals. Option (C) is accurate as electrons fill orbitals in order of increasing energy according to the Aufbau principle.

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