Answer : A substance that can donate a pair of electrons to form a covalent bond is known as a(n) Lewis-base.
Explanation :
According to the Lewis acid-base theory,
Lewis acid : It is a substance that can accepts pairs of electrons to form a covalent bond.
Lewis-base : It is a substance that can donates pairs of electrons to form a covalent bond.
For example :
\(H^++OH^-\rightarrow H_2O\)
In this reaction, \(H^+\) ion is Lewis-acid and \(OH^-\) ion is a Lewis-base. The \(OH^-\) ion donates electrons to \(H^+\) ion to form \(H_2O\).
Hence, a substance that can donate a pair of electrons to form a covalent bond is known as a(n) Lewis-base.
