Question

Identify the element(s) having two electrons in the $\text{K}$ shell of its atom.

• A. Hydrogen atom
• B. Helium dipositive ion
• C. Helium atom
• D. Aluminium atom

Answer 1

Answer: (C), (D)

The correct options are
C

Helium atom

D

Aluminium atom

Since the electrons in atoms are filled in the lower orbits first and then in higher energy orbits, all the atoms except for hydrogen will have two electrons in its $\text{K}$ shell. Helium has exactly two electrons, all of them in the $\text{K}$ shell. All the higher elements have 2 electrons in $\text{K}$ shell with other shells being fully or partially filled.