In organic reactions,sodium in liquid ammonia is used as

Charges of $+\frac{10}{3} \times 10^{-9} \text{ C}$ are placed at each of the four corners of a square of side $8 \text{ cm}$. The potential at the intersection of the diagonals is:

If the lines $4x + 3y - 1 = 0$,$x - y + 5 = 0$,and $kx + 5y - 3 = 0$ are concurrent,then $k$ is equal to:

Example of a biodegradable polymer pair is

Which of the following pairs represents linkage isomerism?

The basis of the quantum mechanical model of an atom is