Question

Define : (a) Covalent bond (b) Catenation

Answer 1

covalent bond = bond which is made by sharing of atoms.
catenation = property to make very long chain by sharing electrons between single atoms such as carbon

Answer 2

Covalent bond : A bond which is formed by the sharing of atoms (it is sharing not transferring)
Catenation : it is the property of forming bonds with atoms of same elements