$A$ group of species with a common ancestor is known as:

If $\vec{a}, \vec{b}$ and $\vec{c}$ are vectors with magnitudes $2, 3$ and $4$ respectively,then the best upper bound of $|\vec{a}-\vec{b}|^2+|\vec{b}-\vec{c}|^2+|\vec{c}-\vec{a}|^2$ among the given values is

Which of the following compounds is not chiral?

Phosgene is formed slowly from which one of the following on exposure to air and sunlight?

Statement $A$: Helium and Beryllium have the same outer electronic configuration of the type $ns^2$.
Reason $R$: Both are chemically inert.

Along the $x$-axis,three charges $\frac{q}{2}, -q$ and $\frac{q}{2}$ are placed at $x=0, x=a$ and $x=2a$ respectively. The resultant electric potential at a point $P$ located at a distance $r$ from the charge $-q$ (where $r > a$) is ($\varepsilon_0$ is the permittivity of free space):