Show that the circuit given in fig. will work as an oscillator at $$f = {1 \over {2\pi RC}},$$ if $${R_1} = 2{R_2}$$

In the circuit of figure $${R_s} = 2\,k\Omega ,$$ $${R_L} = 5\,k\Omega $$ For the op-amp $$A = {10^5},$$
$${R_i} = 100\,k\Omega ,\,\,{R_0} = 50\,k\Omega .$$ For $${V_0} = 10V.$$
Calculate $${V_S}$$ and $${{{V_0}} \over {{V_S}}}$$ and estimate the input resistance of the circuit,

Match the following:
List - $${\rm I}$$ (Circuit)

List - $${\rm II}$$ (Functions)
$$(P)$$$$\,\,\,\,\,$$ High-pass filter
$$(Q)$$$$\,\,\,\,\,$$ Amplifier
$$(R)$$$$\,\,\,\,\,$$ Comparator
$$(S)$$$$\,\,\,\,\,$$ Low-pass filter

One of the applications of current mirror is