Valency and Ions MCQs

Q1. A student examines an atom of sodium and finds 1 electrons occupying its outermost shell; what combining capacity does this give the atom?

• A.7
• B.1
• C.2
• D.3

Answer: B. 1

Valency is the combining capacity set by the octet rule. atoms with four or fewer valence electrons tend to lose them, so valency equals the number of outer electrons, 1. So the valency of sodium is 1.

Q2. On drawing the Bohr model of magnesium, a learner counts 2 dots in the valence ring; from this picture, what is the valency of the element?

• A.6
• B.2
• C.3
• D.1

Answer: B. 2

Valency is the combining capacity set by the octet rule. atoms with four or fewer valence electrons tend to lose them, so valency equals the number of outer electrons, 2. So the valency of magnesium is 2.

Q3. While revising late at night, a pupil notes that aluminium keeps 3 electrons in its furthest orbit; what valency follows from that arrangement?

• A.4
• B.2
• C.5
• D.3

Answer: D. 3

Valency is the combining capacity set by the octet rule. atoms with four or fewer valence electrons tend to lose them, so valency equals the number of outer electrons, 3. So the valency of aluminium is 3.