Question

Which of the following elements possesses variable valency?

• A. Fluorine$\mathbf{\left(}\mathbf{F}\mathbf{\right)}$
• B. Sodium$\mathbf{\left(}\mathbf{Na}\mathbf{\right)}$
• C. Iron$\mathbf{\left(}\mathbf{Fe}\mathbf{\right)}$
• D. Silicon$\mathbf{\left(}\mathbf{Si}\mathbf{\right)}$

Answer 1

The correct option is C

Iron$\mathbf{\left(}\mathbf{Fe}\mathbf{\right)}$

The explanation for the correct options:

C) Valency: The combining capacity of an element (No.of electrons gained or lost by the element) is known as Valency.

• Example:- Iron shows two valencies 2 and 3 as${\mathbf{Fe}}^{\mathbf{+}\mathbf{2}\mathbf{}}\mathbf{}$(Lose of two electrons)${\mathbf{Fe}}^{\mathbf{+}\mathbf{3}}$(lose of three electrons)

Variable valency: If the element shows more than one valency that is known as Variable valency.

• Therefore Iron shows (Variable valency) two valencies ${\mathbf{Fe}}^{\mathbf{+}\mathbf{2}\mathbf{}}\mathbf{}$and ${\mathbf{Fe}}^{\mathbf{+}\mathbf{3}}$

The explanation for the incorrect options

A) The valency of fluorine is one (Carries one unit of negative charge) - ${\mathbf{F}}^{\mathbf{-}}$

B) The valency of Sodium is one (Carries one unit of positive charge) - ${\mathbf{Na}}^{\mathbf{+}}$

C) The valency of Silicon is four (Carries four units of positive charge) - ${\mathbf{Si}}^{\mathbf{+}\mathbf{4}}$

Hence option (C) is correct.