$\begin{array}{l}\sqrt{\frac{L}{C}}\\ & \frac{}{}\end{array}$

$\begin{array}{ll}\text{(b)}& \frac{C}{R}\\ \end{array}$

$\begin{array}{l}\frac{1}{\sqrt{RC}}\end{array}$

$\begin{array}{l}\text{For RC circuits, time constant is,}\tau =RC\text{has unit of time,}\\ \text{so,}\frac{1}{RC}\text{has a unit of frequency,}\\ \text{similar for LC oscillations,}\tau =\sqrt{LC}\\ \text{for RL circuit,}\tau =\frac{L}{R}\\ \text{so,}\frac{R}{L}\text{and}\frac{1}{\sqrt{LC}}\text{has units of frequency.}\end{array}$