Question

How many compounds are formed by electrovalency?
KCI, NaCl, CsCl, ${{\text{O}}_{\text{2}}}$ , ${{\text{N}}_{\text{2}}}$ , ${\text{C}}{{\text{O}}_{\text{2}}}$ , BaO, ${\text{CaC}}{{\text{l}}_{\text{2}}}$, ${{\text{H}}_{\text{2}}}{\text{O}}$
A. 2
B. 3
C. 4
D. 5

Answer 1

Hint: Electrovalency is when two or more highly electropositive and highly electronegative atoms react to form a single compound. Therefore, find the compounds containing either highly electropositive or highly electronegative atoms, for eg, sodium (Na), potassium (K), cesium (Cs), calcium (Ca) and barium (Ba) are highly electropositive and chlorine (Cl) and oxygen (O) are highly electronegative.

Complete step by step answer:
5 of the given compounds are formed by electrovalency.
They are: KCI, NaCl, CsCl, BaO and ${\text{CaC}}{{\text{l}}_{\text{2}}}$
Electrovalency is when two or more highly electropositive and highly electronegative atoms react to form a single compound. The compounds containing electrovalent or ionic bonds are termed as Electrovalent or Ionic Compounds.
There are a few conditions for the formation of an electrovalent bond. They are:
1) Low ionization energy of an electropositive atom.
2) High electron affinity of an electronegative atom.
3) Large difference in electronegativity or electropositivity.
4) High lattice energy of both the atoms.

So, the correct answer is Option D.

Note: Remember that, large difference in electronegativity or electropositivity, high lattice energy, low ionization energy or high electron affinity of an atom etc are the factors conditioning the formations of an electrovalent or ionic compound. For example, the large difference in electronegativity or electropositivity of Na and Cl atoms is the reason for the formation of NaCl.