Question

Transitional elements exhibit variable valencies because they release electrons from the following orbits :

• A. $ns$ orbit
• B. $ns$ and $np$ orbits
• C. $(n-1)d$ and $ns$ orbits
• D. $(n-1)d$ orbit

Answer 1

Answer: (C)

$(n-1)d$ and $ns$ orbits

The ability of the transition metals to exhibit variable valency is generally attributed to the availability of more electrons in the $(n-1)d$ orbitals which are closer to the outermost $ns$ orbital in energy levels.