Match the items in columns $$I$$ and $$II$$.

Column $$I$$
$$P:$$ Centrifugal compressor
$$Q:$$ Centrifugal pump
$$R:$$ Pelton wheel
$$S:$$ Kaplan turbine

Column $$II$$
$$1:$$ Axial flow
$$2:$$ Surging
$$3:$$ Priming
$$4:$$ Pure impulse