Answer is: D.silicon and phosphorus.
When the electronegativity difference is greater, the bond polarity is increasing..
Electronegativity (χ) is a property that describes the tendency of an atom to attract a shared pair of electrons.
Atoms with higher electronegativity attracts more electrons towards it, electrons are closer to that atom.
A) Δχ(Bi-S) = 2.5 - 2.0 = 0.5; polar covalent.
B) Δχ(C-O) = 3.5 - 2.5 = 1.0; polar covalent.
C) Δχ(N-O) = 3.5 - 3 = 0.5; polar covalent.
D) Δχ(Si-P) = 2.2 - 1.9= 0.3; nonpolar covalent.
