\(\left(\dfrac{1}{2}\right)^{300}=\dfrac{1}{2^{300}}=\dfrac{1}{\left(2^3\right)^{100}}=\dfrac{1}{8^{100}}\)
\(\left(\dfrac{1}{3}\right)^{200}=\dfrac{1}{3^{200}}=\dfrac{1}{\left(3^2\right)^{100}}=\dfrac{1}{9^{100}}\\ \)
\(\dfrac{1}{8^{100}}>\dfrac{1}{9^{100}}\\ \Rightarrow\left(\dfrac{1}{2}\right)^{300}>\left(\dfrac{1}{3}\right)^{200}\)