Question

In the ground state, an element has 13 electrons in its ''M shell''. The element is

• A. Copper
• B. Chromium
• C. Nickel
• D. Iron

Answer 1

Answer: (B)

Chromium

Answer 2

Electrons in M shell (or 3rd shell) = 13
$\therefore$ Configuration of M shell : $3s^2\, 3p^6\, 3d^5$
Therefore, the element can be either Cr(Z = 24)
or Mn (Z = 25). As Mn is not one of the options given, Cr is the correct answer.