The $\pi$-acid ligand which uses its $d$-orbital during synergic bonding in its complex compound is

$A$ photocell is a device used to:

If tangents are drawn from any point on the circle $x^2+y^2=25$ to the ellipse $\frac{x^2}{16}+\frac{y^2}{9}=1$,then the angle between the tangents is

Photo-oxidation of chlorophyll is called

$A$ $Ge$ specimen is doped with $Al$. The concentration of acceptor atoms is $\sim 10^{21} \, \text{atoms}/m^3$. Given that the intrinsic concentration of electron-hole pairs is $\sim 10^{19}/m^3$, the concentration of electrons in the specimen is:

In the given circuit,if point $C$ is connected to the earth and a potential of $+2000 \, V$ is applied to point $A$,what is the potential of point $B$ in volts?