Question

An atom with 4 protons and 5 neutrons will have a valency of :

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The correct option is B

2

Explanation for the correct answer

Option B

• The combining capacity of an element to form a stable bond is known as the valency of the element.
• Valency of the element depends upon the valence electrons.
• For the elements having valence electrons 1,2 or 3, valency equals the number of valence electrons.
• Here the number of protons = 4
• Number of electrons = Number of protons = Atomic number = 4
• Electronic configuration of an element with atomic number 4 = $$\begin{gathered} \mathrm{K}\mathrm{L} \\ 22 \end{gathered}$$
• Valence electrons = 2
• Hence valency of an element with 4 protons and 5 neutrons = 2

Conclusion: Hence option B is correct, An atom with 4 protons and 5 neutrons will have a valency of two.