Question

Which of the following will be the strongest bond ?
(A) F – O
(B) O – Cl
(C) N – H
(D) O – H

Answer 1

Hint: A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may have formed from the electrostatic force of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds.

Complete answer:
There are four types of chemical bonds or interactions
1. Ionic bond
2. Covalent bond
3. Hydrogen bond
4. Vander waals interactions
Ionic and covalent bonds are strong interactions that require a larger energy input to break apart whereas hydrogen and van der waals interactions are weak.
1. Ionic bond : Ionic bonds are formed by the interaction of metal (s - block ) and nonmetal. It involves a transfer of electrons, one atom gain electron carries negative charge (anion) while one atom loses electron and carries positive charge (cation). Because of positive-negative charge, an electrostatic force of attraction exhibits, and the atoms bond together to form a molecule.
2. Covalent bond : Covalent bonds are generally formed by the interaction of non-metals. A covalent bond involves the sharing of electrons between two atoms. The pair of shared electrons from a new orbit that extends around the nuclei of both atoms, producing a molecule.
3. Hydrogen bond : The hydrogen atom in that bond has a slightly positive charge. This is because the shared electron is pulled more strongly toward the other element and away from the hydrogen nucleus. Because the hydrogen is slightly positive. It will be attracted to neighbouring negative partial charge. A weak interaction occurs between positive and negative charge. This is called hydrogen bond.
4. Vander waals interactions : Like hydrogen bonds, Vander waals interaction are weak attractions or interactions between molecules. They occur between polar, covalently bound, atoms in different molecules.
So, from the above information, a strong chemical bond is formed by sharing or transfer of electrons.
The strength of strong bonds differ due to the difference in electronegativity of constituent elements.
The greater the difference between the electronegativity values of two elements joined by a bond the greater the polarity of that bond and stronger the bond as well.
Bond strength $ \propto $ electronegativity difference.
Let’s see the electronegativity differences on by one
$F - O = 0.5$
$O - Cl = 0.3$
$N - H = 0.8$
$O - H = 1.2$
Therefore, $O - H$ bond has greater electronegativity difference. So the strongest bond is $O - H$.

Hence, the correct answer is (D) $O - H$.

Note: Atoms with high electronegativity have smaller electronegativity difference. If we consider only electronegativity to solve this question then the answer will go wrong. Therefore we consider electronegativity differences.