Which is the smallest blood vessel in the body?

Observe the following statements regarding the purification of bauxite:
$I$. During Hall's process,silica is removed as $Si$ (vapour).
$II$. Bauxite ore contaminated with $Fe_2O_3$ is purified in Baeyer's process.
$III$. During Serpeck's process,$AlN$ is formed.
The correct answer is:

Cataract and skin cancer are caused by

Two wires of the same material and length but diameters in the ratio $1:2$ are stretched by the same force. The elastic potential energy per unit volume for the wires, when stretched by the same force, will be in the ratio: (in $:1$)

The degree of the differential equation $\frac{d^2y}{dx^2} + 3\left[ \frac{dy}{dx} \right]^2 = x^2 \log \left[ \frac{d^2y}{dx^2} \right]$ is

If $a, b$ and $c$ are the roots of $x^3+4x+1=0$,then $\frac{1}{a+b}+\frac{1}{b+c}+\frac{1}{c+a}=$