Question

There are many elements in the periodic table which exhibit variable valency. This is a particular characteristic of :

• A. representative elements
• B. transition elements
• C. noble gases
• D. non-metals

Answer 1

The correct option is B transition elements

Transition elements show variable valency. (n-1) d and ns electrons are of nearly same energy level. Most of these electrons take part in chemical bonding. Thus, they show various valencies.

Example: iron with outer electronic configuration $3d^{6}4s^2$ show common valencies of $+2$ and $+3$.