Question

Element X exhibits different valencies. What happens when element X participates in different reactions?

• A. change in number of protons that react
• B. change in number of electrons that react
• C. change in number of neutrons that react
• D. change in number of both protons and neutrons that react

Answer 1

The correct option is B change in number of electrons that react

Valency is the combining capacity of an element. Some elements exhibit variable valency. Depending upon valency of the element that is required to acheive stability, the number of electrons that take part in a reaction is decided.
For example, iron has variable valency. Depending upon the condition of the reaction, either 2 or 3 electrons may take part in a reaction.