Identify the plant and structure marked $A$ and $B:-$

If $\triangle ABC$ is right-angled at $A$,then $r_2+r_3$ is equal to

If $\tan x + \tan \left(x + \frac{\pi}{3}\right) + \tan \left(x + \frac{2\pi}{3}\right) = 3$,then $\tan 3x$ is equal to

For $x \in \mathbb{R}$,the range of $3 \cos (4x - 5) + 4$ lies in the interval

$A$ bullet of mass $10 \ g$ pierces through a plate $A$ of mass $500 \ g$ and then gets embedded into a second plate $B$ of mass $1.49 \ kg$ as shown in the figure. Initially,the two plates $A$ and $B$ are at rest and move with the same velocity after the collision. The percentage loss in the initial kinetic energy of the bullet,when it is between the plates $A$ and $B$,is . . . . . .
(Neglect any loss of material of the plates during the collision)

What is the volume (in litres) of oxygen required at $STP$ to completely convert $1.5 \ mol$ of sulphur into sulphur dioxide?