what is the total charge?

Explanation:

Step1: Identify charges

Assume the red particles are protons (charge +1 each) and blue particles are electrons (charge - 1 each). There are 2 protons and 2 electrons.

Step2: Calculate total charge

The total charge $Q$ is the sum of the charges of all particles. The charge of protons is $2\times(+ 1)=+2$ and the charge of electrons is $2\times(-1)= - 2$. So $Q=2\times(+1)+2\times(-1)=2 - 2$.

Answer:

0