Question

which of the following exhibit variable valency a) ca,na b)mg,fe. c)fe,mn. d)zn,sn​

Answer 1

Answer :

⇒ All transition elements except the first and last member of each series show variable valencies because difference of energy in the (n - 1)d and ns orbitals is very little and electrons from both the orbitals can be used for bond formation.

⇒ Elements of d - block are called as transition elements.

✭ Calcium (Ca) :

➝ Block : s

➝ Valency : (+2)

✭ Sodium (Na) :

➝ Block : s

➝ Valency : (+1)

✭ Magnesium (Mg) :

➝ Block : s

➝ Valency : (+2)

✭ Iron (Fe) :

➝ Block : d

➝ Velency : (+2)(+3)(+4)(+6)

✭ Manganese (Mn) :

➝ Block : d

➝ Valency : (+2)(+3)(+4)(+5)(+6)(+7)

✭ Zinc (Zn) :

➝ Block : d

➝ Valency : (+2)

✭ Tin (Sn) :

➝ Block : p

➝ Valency : (+4)

Correct answer : (C) Fe & Mn