Companion cells are closely associated with $..........$.

If $C$ is the midpoint of $AB$ and $P$ is any point outside $AB$,then:

The following compound is used as:

The number of common tangents to the circles $x^2+y^2-4x-6y-12=0$ and $x^2+y^2+6x+18y+26=0$ is

The value of $\sqrt{12\sqrt{5} + 2\sqrt{55}}$ is

Which of the following statements is correct for the peroxide ion $(O_2^{2-})$?
$A.$ It has completely filled antibonding molecular orbitals.
$B.$ It is diamagnetic.
$C.$ It has a bond order of $1$.
$D.$ It is isoelectronic with Neon.