Answer:
c. differ in electronegativity
Explanation:
Covalent bond:
It is formed by the sharing of electron pair between bonded atoms.
The atom with larger electronegativity attract the electron pair more towards it self and becomes partial negative while the other atom becomes partial positive.
For example:
In water the electronegativity of oxygen is 3.44 and hydrogen is 2.2. That's why electron pair attracted more towards oxygen, thus oxygen becomes partial negative and hydrogen becomes partial positive
. The bond is polar.
When the elctronegativity difference is 0.4 or less than 0.4 the bond is non polar.
if the electronegativity difference is greater than 0.4 the bond is polar.
