Electronic Configuration — Homi Bhabha Exam Chemistry MCQs with Solutions
Free Homi Bhabha Exam Chemistry Electronic Configuration MCQs with step-by-step solutions (7 questions). Part of Periodic Classification & Chemical Bonding. Practise online on Prepizo — no login needed.
▶ Practise Electronic Configuration online (free)
Questions with solutions
Q1 — Electronic Configuration · medium · numerical
The maximum number of electrons that the first shell (K) of an atom can hold is:
A. 2 ✓ Correct
B. 1
C. 8
D. 18
Solution: By the $2n^2$ rule, the K shell ($n=1$) holds $2 \times 1^2 = 2$ electrons.
Q2 — Electronic Configuration · medium · numerical
The maximum number of electrons in the second shell (L) is:
A. 32
B. 8 ✓ Correct
C. 2
D. 18
Solution: For $n=2$, maximum $= 2 \times 2^2 = 8$ electrons.
Q3 — Electronic Configuration · hard · theory
The electronic configuration of a sodium atom (atomic number 11) is:
A. 2, 9
B. 2, 8, 1 ✓ Correct
C. 2, 8, 8
D. 8, 2, 1
Solution: Filling shells: 2 in K, 8 in L, 1 in M gives 2, 8, 1.
Q4 — Electronic Configuration · medium · theory
The electrons present in the outermost shell of an atom are called:
A. core electrons
B. nucleons
C. valence electrons ✓ Correct
D. free electrons
Solution: Outer-shell electrons are valence electrons and decide chemical behaviour.
Q5 — Electronic Configuration · hard · numerical
The number of valence electrons in a chlorine atom (configuration 2, 8, 7) is:
A. 8
B. 2
C. 17
D. 7 ✓ Correct
Solution: The outermost shell has 7 electrons, so chlorine has 7 valence electrons.
Q6 — Electronic Configuration · hard · theory
An atom is chemically stable when its outermost shell contains ______ electrons (octet), except for the first shell which needs 2:
A. 4
B. 18
C. 2
D. 8 ✓ Correct
Solution: A complete octet (8 electrons) in the outer shell gives special stability (duplet for the first shell).
Q7 — Electronic Configuration · medium · theory
An element with the electronic configuration 2, 8, 8 is:
A. hydrogen
B. a noble gas (argon) ✓ Correct
C. a reactive metal
D. a halogen
Solution: The complete outer octet (2, 8, 8) is that of the noble gas argon (atomic number 18).