Answer
The charge of the particle is $~~1.8\times 10^{-6}~C$
Work Step by Step
The flux is $2.0\times 10^5~N~m^2/C$ when the enclosed charge within the Gaussian sphere is the charge of the particle.
We can find the charge of the particle:
$\Phi = \frac{q}{\epsilon_0}$
$q = \Phi ~\epsilon_0$
$q = (2.0\times 10^5~N~m^2/C)(8.854\times 10^{-12}~F/m)$
$q = 1.8\times 10^{-6}~C$
The charge of the particle is $~~1.8\times 10^{-6}~C$.
