What is the ionic strength of 0.2 M Na2HPO4 in a solution?

=1/2 [0.2x2x1*2 + 0.2x1x(-2)*2]

=1/2 [0.4 + 0.8]
=1/2 [1.2]
= 0.6

Ionic strength of 0.2 M Na2HPO4 is 0.6 M

0.6 M is the ionic strength.

0.2 M * 2 *(1)^2+ 0.2 M * 1 * (-1)^2
= 0.6

https://en.wikipedia.org/wiki/Ionic_strength

The ionic strength of a 0.2 M Na2HPO4, solution will

be

I=1/2{C1Z1^2+C2Z2^2+......}

=1/2{0.2×2×1^2+0.2×1×(-1)^2+0.2×1×(-3)^2
=1/2{0.4+0.2+1.8}
=1/2{2.4}
=1.2M

0.8