Valency — Homi Bhabha Class 9 Chemistry MCQs with Solutions
Free Homi Bhabha Class 9 Chemistry Valency MCQs with step-by-step solutions (8 questions). Part of Atoms, Molecules & Structure. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Valency · medium · theory
The combining capacity of an element is called its:
A. mass number
B. atomic number
C. atomicity
D. valency ✓ Correct
Solution: Valency is the number of bonds an atom can form, i.e. its combining capacity.
Q2 — Valency · medium · theory
The valency of oxygen in most of its compounds is:
A. 2 ✓ Correct
B. 1
C. 3
D. 4
Solution: Oxygen typically forms two bonds, so its valency is 2 (e.g. H₂O).
Q3 — Valency · hard · numerical
Aluminium has a valency of 3 and oxygen a valency of 2. The formula of aluminium oxide is:
A. AlO₂
B. Al₂O₃ ✓ Correct
C. AlO
D. Al₃O₂
Solution: Cross-multiplying the valencies (Al = 3, O = 2) gives Al₂O₃.
Q4 — Valency · medium · theory
The valency of carbon, which allows it to form four bonds, is:
A. 4 ✓ Correct
B. 1
C. 3
D. 2
Solution: Carbon has 4 electrons in its outer shell and a valency of 4 (tetravalent).
Q5 — Valency · hard · numerical
Calcium (valency 2) combines with chlorine (valency 1). The formula of calcium chloride is:
A. Ca₂Cl₃
B. CaCl
C. Ca₂Cl
D. CaCl₂ ✓ Correct
Solution: One Ca (valency 2) balances two Cl (valency 1 each), giving CaCl₂.
Q6 — Valency · easy · theory
The valency of an element is best described as:
A. The number of shells in its atom
B. Its atomic mass
C. The number of neutrons in its atom
D. Its combining capacity ✓ Correct
Solution: Valency is the combining capacity of an element, decided by the number of electrons it gains, loses or shares to become stable.
Q7 — Valency · medium · theory
An element X has 2 electrons in its outermost shell. What is its most likely valency?
A. 2 ✓ Correct
B. 6
C. 0
D. 8
Solution: With 2 electrons in the outer shell, X loses both to reach a stable configuration, so its valency is 2.
Q8 — Valency · hard · theory
Aluminium has a valency of 3 and the sulphate group (SO4) has a valency of 2. Using the criss-cross method, the correct formula of aluminium sulphate is:
A. Al3(SO4)2
B. Al2(SO4)3 ✓ Correct
C. Al(SO4)2
D. AlSO4
Solution: Crossing the valencies, aluminium (3) and sulphate (2) exchange numbers to give Al2(SO4)3, which is electrically neutral.