Question

Water and benzene have the same surface tension.
A.True
B.False

Answer 1

Hint: We know that surface tension is the phenomenon in which liquid particles at the surface are attracted by the bulk of the liquid that cause the reduction in surface area. The unit used to measure surface tension is dynes/cm.

Complete step by step answer:
Let’s first understand the structure of benzene and water molecules. Benzene is a compound of molecular formula ${{\rm{C}}_{\rm{6}}}{{\rm{H}}_{\rm{6}}}$ and structure of benzene is,

Water is a compound of molecular formula ${{\rm{H}}_{\rm{2}}}{\rm{O}}$. The structure of water is,

Now, come to the question. The surface tension is because of the intermolecular force within a substance. So, more intermolecular force of attraction means more surface tension of the compound.

Now, we have to compare the surface tension of benzene and water. Benzene is a nonpolar molecule as the bonding in benzene is C-H and C-C and there is not much difference of electronegativity between carbon and hydrogen atoms. In the benzene, there is also no hydrogen bonding and dipole. So, the intermolecular force of attraction in benzene is the weakest force that is London's dispersion force. So, the surface tension in benzene is low.
Water is a polar molecule. It also has four intermolecular hydrogen bonding. The hydrogen bonding in water can be shown as below:

Due to the four intermolecular hydrogen bonding, intermolecular force in water is very high. So, the surface tension in water is very high.

Therefore, water and benzene have different surface tension.

Hence, correct answer is option B, that is, false.

Note: Hydrogen bond is a chemical bond in which formation of a covalent link of hydrogen atoms with other electronegative atoms, such as, fluorine, nitrogen and oxygen atoms takes place in the same or another molecule.