Answer:
+2.05 x 10²²
Explanation:
Cations are positive, and anions are negative. We can see there are more cations than anions, so the answer will be a positive charge.
The exponents are the same, so it's really just a simple subtraction problem:
- 4.09 x 10²²
- - 2.04 x 10²²
- +2.05 x 10²²