In the following questions pick the odd thing out.
Each of the questions follows a definite pattern, observe the same and fill in the blanks with suitable ones.
$$\frac{8}{3}, \frac{25}{12}, \frac{5}{9}$$, ______, $$\frac{32}{21}, \frac{81}{56}$$
225, 16, 169, 36, 121, 64, 81, _________