$A$ compound of mercury used in cosmetics,in Ayurvedic and Yunani medicines and known as Vermilion is

What are $X$ and $Y$ respectively in the following reaction?
$Z$-product $\stackrel{Y}{\longleftarrow} 2$-butyne $\stackrel{X}{\longrightarrow} E$-product

The basic unit of classification for plants and animals is ....

The perpendicular distance from the point $(1, \pi)$ to the line joining $(1, 0^{\circ})$ and $(1, \frac{\pi}{2})$ (in polar coordinates) is:

Consider a solid insulating sphere of radius $R$ with charge density varying as $\rho = \rho_0 r^2$ (where $\rho_0$ is a constant and $r$ is measured from the centre). Consider two points $A$ and $B$ at distances $x$ and $y$ respectively from the centre,such that $x < R$ and $y > R$. If the magnitudes of the electric fields at points $A$ and $B$ are equal,then:

The volume in $mL$ of $0.1 M$ solution of $NaOH$ required to completely neutralize $100 \ mL$ of $0.3 M$ solution of $H_3PO_3$ is: