Question

Which of the following substances has polar covalent bonds?

Options are CH4, KBR, NH3, CaF2

Answer 1

Covalent bond : The bond formed due to sharing of pairs of electrons.

For example H and H form bond and H2 molecule is formed. In H2 molecule bond is covalent.

In it, each contributes 1 electrons from their outer shell.

But when in this type of molecule there is more electronegativity difference then the bond formed between them is called as polar covalent. Polar is the word comes from the poles (partial positive and partial negative charges on atoms).

For example HCl ; there is much difference in electronegativity of H and Cl so H bears partial positive charge and Cl partial negative and due this polar nature it is called as polar covalent bond.

In given molecules N-H bond is polar covalent in ammonia due to difference in electronegativity in N and H.

In case of CH4 there is not such a large difference so CH4 is not in the choice.

KBr and CaF2 are ionic compounds so these form ionic bond and they are so removed our choices and the answer is : NH3