The coordination number of a metal crystallizing in a hexagonal close-packed structure is

If the polar of a point on the circle $x^2+y^2=p^2$ with respect to the circle $x^2+y^2=q^2$ touches the circle $x^2+y^2=r^2$,then $p, q, r$ are in

Anthropogenic actions that lead to evolution are the use of:

If a polygon of $n$ sides has $275$ diagonals,then $n$ is equal to

The number of nodal planes in a $p_x$ orbital is

Which organisms obtain nutrition through both photosynthesis and absorption?