What does the part labeled '$A$' in the given figure represent?

The first step of taxonomy is .......... .

Statement$-1$ : Toluene is more reactive than benzene in chlorination.
Statement$-2$ : During the nitration of Toluene $\stackrel{\oplus}{ N } O _2$ acts as electrophile.

Which of the following $0.05 \, M$ aqueous solution will have the lowest freezing point?

If the imaginary part of $\frac{2z+1}{iz+1}$ is $-2$,then the locus of the point representing $z$ in the Argand plane is

In an experiment with $15$ observations on $x$,the following results were available: $\sum x^2 = 2830$ and $\sum x = 170$. One observation that was $20$ was found to be wrong and was replaced by the correct value $30$. Then the corrected variance is: