Question

Which one of these is weakest?
(A) ionic bond
(B) covalent bond
(C) metallic bond
(D) Van der Waal forces

Answer 1

Hint: A bond is a force existing between atoms in a molecule that holds them together. This depends on the fact that some bonds are stronger than the others. It means that some molecules need more force than the other to break down into its subsequent atoms.

Complete step by step solution:
Now, let us discuss the options one by one.
Discussing option (A), an ionic bond is also called an electrovalent bond. Ionic compounds are formed when metals react with non-metals. Once formed, these ions are tightly packed together because their opposite charges attract. This attraction between a positive and negative ion in an ionic compound is nothing but, ionic bond. This bond is mainly stabilised by electrostatic attraction. Thus, these bonds are quite strong.
Discussing option (B), a covalent bond is formed when nonmetals combine with each other to form molecules. Here there is some lowering of energy due to electron sharing. When two atoms come together the valence electrons of each of the atoms will be attracted and shared by the nuclei of both the atoms; as a result, a net strong bonding occurs between the two atoms and is called the covalent bond.
Discussing option (C), metallic bonding is a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons (in the form of an electron cloud of delocalised electrons) and positively charged metal ions. It may be described as the sharing of free electrons among a structure of positively charged ions (cations).
Discussing option (D), Van der Waal forces: Unlike ionic or covalent bonds, these attractions do not result from a chemical electronic bond; they are comparatively weak and therefore more susceptible to disturbance. The van der Waals force quickly vanishes at longer distances between interacting molecules.

Clearly, the correct answer is (D).

Note: Do not confuse Van der Waal forces with ion-dipole force or dipole-dipole force. Dipole-dipole forces occur between molecules with permanent dipoles (i.e., polar molecules). For molecules of similar size and mass, the strength of these forces increases with increasing polarity.