Question

Which of the following is not a characteristic of covalent bond.
A. It has low melting point and boiling point.
B. It is formed between two atoms having no or very small electronegativity difference.
C. They have no definite geometry
D. They are generally insoluble in water.

Answer 1

Hint: A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared paired or bonding pairs. If you are aware about the basic characteristic of this bond, then you can easily spot the right option.

Complete step-by-step answer:
This question is based on the properties of covalent bonds. So, to answer this we will solve it option by option. Let us take the first option.

A. It has low melting and boiling point: we know that covalent bonds are very stable and the interatomic forces are quite strong, but the intermolecular forces between covalent compounds are weak. Since, the forces are weak they need only little energy to break. Heat is a form of energy. Due to weak bonds, they have low melting and boiling point. So, this option is correct.

B. Covalent bond involves sharing of electrons. So, for this the electronegativity difference of two atoms should be very small. If one atom is very much electronegative, then instead of sharing it will attract the electron pairs and as a result ionic bonds will be formed. Hence, this statement is true.

C. They have no definite geometry: covalent bonds are directional in nature and as a result they have definite geometry and shape. Hence, this statement is wrong.

D. Covalent Compounds are generally non polar and we know that water is a polar solvent. Now, we also know that there is a principle which states ‘’like dissolves like’’. So polar compounds will be dissolved only in polar solvents. Since covalent compounds are non-polar they are not soluble in polar water.
Hence, this statement is also true.

Hence, the correct answer is option ‘A’.

Note: There are other properties of covalent compounds. Covalent compounds do not conduct electricity, they have lower enthalpies of vaporization and fusion, contain energy of about $80kCal$ per mole and they are very powerful bonds that exist between atoms.