The phenomenon of 'industrial melanism' demonstrates:

The curves $(a), (b), (c)$ and $(d)$ show the variation between the applied potential difference $(V)$ and the photoelectric current $(i),$ at two different intensities of light $(I_1 > I_2).$ In which figure is the correct variation shown?

The supportive skeletal structures in the human external ears and in the nose tip are examples of

In the expansion of $(1+x)^n$,the coefficients of $p$-th and $(p+1)$-th terms are respectively $p$ and $q$. Then $p+q=$

Which of the following exhibits a haplontic life cycle?

The collector plate in an experiment on the photoelectric effect is kept vertically above the emitter plate. $A$ light source is turned on,and a saturation photocurrent is recorded. An electric field is then switched on,which has a vertically downward direction.