Chemistry Atomic Structure SET 2019
PMDC Verified Question 76 of 95
Which of the following element in its atomic state has electrons fully occupying first two spherically symmetrical orbitals?
A
Oxygen
B
Helium
C
Carbon
D
Beryllium
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Beryllium
Concept: Spherically symmetrical orbitals correspond to \(s\)-orbitals (\(l=0\)).

Formula: None required.

Solution:
  • The first two spherically symmetrical orbitals are the \(1s\) and \(2s\) orbitals.
  • Fully occupying both means filling them with a total of 4 electrons: \( 1s^2, 2s^2 \).
  • The element with an atomic number of 4 is Beryllium (Be).


Why other options are incorrect: Helium only fully occupies the first \(s\)-orbital (\(1s^2\)). Oxygen and Carbon have electrons in \(p\)-orbitals, going beyond just the first two \(s\)-orbitals.

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