The middle term in the expansion of $\left( \dfrac { 2x^{ 2 } }{ 3 } +\dfrac { 3 }{ { 2 }x^{ 2 } } ; \right) ^{ 10 }$ is& ;

$(\frac{2x^{2}}{3}+\frac{3}{2x^{2}})^{10}$

$\Rightarrow (a+b)^{n} = ^{n}C_{0}a^{n}+^{n}4a^{n}b+--+^{n}C_{\pi }a^{n-\pi }b^{\pi }+-^{n}C_{n}b^{n}$

$\therefore$ middle term is $6^{th}$ here, so :

$= 7_{6} \Rightarrow ^{10}C_{5} (\frac{2x^{2}}{3})^{10-5} (\frac{2}{2x^{2}})^{5}$

$\Rightarrow \dfrac{10\times 9\times 8\times 7\times 6}{5\times 4\times 5\times 2\times 1} (\dfrac{2x^{2}}{3^{8}})^{5} (\dfrac{2}{2x^{2}})^{5}$

$\Rightarrow 4\times 63\times 2 (1)$

$\Rightarrow 252\times 1$

$\Rightarrow 252$

(Option B)