Resulting charge on each sphere:
When two identical spheres carrying charges touch, the charges redistribute evenly over the two spheres. So, the resulting charge on each sphere will be (0.8 + (-0.3)) / 2 = 0.75 coulomb.
Number of elementary charges on each sphere:
The elementary charge (e) is a fundamental constant of nature with a value of approximately 1.6 x 10^-19 coulombs. To find the number of elementary charges on each sphere, divide the charge on the sphere by the elementary charge:
0.75 coulombs / 1.6 x 10^-19 coulombs/charge = 4.7 x 10^18 charges.
So, each sphere will have 4.7 x 10^18 elementary charges.