Which of the following vitamins is water-soluble?

Which has the maximum number of molecules among the following?

If the wavelengths of maximum intensity of radiations emitted by the sun and the moon are $0.5 \times 10^{-6} \ m$ and $10^{-4} \ m$ respectively,the ratio of their temperatures is:

Arrange the proper pair.

Column-$I$	Column-$II$
$(a)$ Land snail	$(1)$ Urea
$(b)$ Cartilaginous fishes	$(2)$ Uric acid
$(c)$ Marine fishes	$(3)$ Ammonia

What do you understand by isoelectronic species? Name a species that will be isoelectronic with each of the following atoms or ions.
$(i)$ $F^{-}$ $(ii)$ $Ar$ $(iii)$ $Mg^{2+}$ $(iv)$ $Rb^{+}$

The angle between the curves $y^2=4x+4$ and $y^2=36(9-x)$ is (in $^{\circ}$)