Question

Which of the following contains (electrovalent) and polar (covalent) bond
A) $ C{H_4} $
B) $ {H_2}{O_2} $
C) $ N{H_4}Cl $
D) $ HCN $

Answer 1

Hint: A covalent bond is formed when two atoms share electrons. The key distinction between an electrovalent and a covalent bond is that an electrovalent bond is formed when two atoms are attracted to each other electrostatically, while a covalent bond is formed when two atoms exchange electrons.

Complete answer:
1) The $ N - H $ bond in $ N{H_4}Cl $ is polar due to a significant electronegativity difference between $ N(3.0) $ and $ H(2.1) $ .
2) The $ H - C $ and $ C - N $ bonds in $ HCN $ are polar due to the electronegativity difference between $ C(2.5) $ and $ N(3.0) $ for the $ H - C $ bond and $ C(2.5) $ and $ H(2.1) $ for the $ C - N $ bond.
3) Because of the electronegativity difference between $ O(3.5) $ and $ H(1.5) $ , the $ O - H $ bond in $ {H_2}{O_2} $ is polar $ (2.1) $ . The $ O - O $ bond, on the other hand, is non-polar.
4) The $ C - H $ bonds in $ C{H_4} $ are also polar.
Hence, the correct option is (C) $ N{H_4}Cl $ .

Note:
When two nonmetal atoms share a pair of electrons, they form a covalent bond. The electrons present are in the atoms' outer shells. Covalent bonds are very strong and take a lot of energy to crack so both nuclei are highly attracted to the shared pair of electrons.