Gold numbers of protective colloids $A$,$B$,$C$ and $D$ are $0.50$,$0.01$,$0.10$ and $0.005$,respectively. The correct order of their protective powers is

The sum of the fourth powers of the roots of the equation $x^3+x+1=0$ is

Ferredoxin is a structural component of which of the following?

$A$ ray of light is incident normally on a glass slab of thickness $5 ~cm$ and refractive index $1.6$. The time taken by a ray to travel from the source to the surface of the slab is the same as the time taken to travel through the glass slab. The distance of the source from the surface is (in $~cm$)

The amplitude of a wave represented by the displacement equation $y = \frac{1}{\sqrt{a}} \sin \omega t \pm \frac{1}{\sqrt{b}} \cos \omega t$ will be

If $z = \frac{y}{x} \left[ \sin \frac{x}{y} + \cos \left( 1 + \frac{y}{x} \right) \right]$,then $x \frac{\partial z}{\partial x}$ is equal to