How is the electronegativity difference used in determining the type of bond that occurs between two atoms?If the difference is between 0 and 1.7,...

The first three statements are
correct.

Since it is the relative tendency of an aom to
attract the bonded electron pair to itself, the electronegativity values are considered
as positive values.

example:  electronegativity values of F
= +4, H = 2.1, O = 3.5, Cl = 3.5  and Na = 0.9
etc.

Ofcourse the differences can be negative. Example the
difference in electronegativity values of O and H = +
1.4

But the difference in electronegativity values of H
and O = - 1.4.

So the fourth statement should be corrected
as follows:

If the difference is between zero and - 1.7
then also the bond is considered as polar covalent
compound.

The fifth statement is corrected
as:

If the difference is greater than 1.7 it is considered
as ionic bond