Which of the following is the strongest reducing agent?

In gel electrophoresis,the separated bands of $DNA$ are cut out and extracted from the gel piece. This step is called

Four thin rods of same mass $M$ and same length $l$ form a square as shown in the figure. The moment of inertia of this system about an axis passing through the centre $O$ and perpendicular to its plane is

The number of triangles that can be formed by choosing the vertices from a set of $12$ points,seven of which lie on the same straight line,is

If the impurity in a metal has a greater affinity for oxygen and is more easily oxidised than the metal,then the purification of metal may be carried out by

Determine the empirical formula of Kevlar,used in making bulletproof vests,if it contains $70.6 \% \, C, 4.2 \% \, H, 11.8 \% \, N$,and $13.4 \% \, O$.