The three-domain system of classification is based on which of the following criteria?

The terminal velocity of a liquid drop of radius $r$ falling through air is $v$. If two such drops are combined to form a bigger drop, the terminal velocity with which the bigger drop falls through air is (ignore any buoyant force due to air).

Consider the reaction:
$Cl_{2(aq)} + H_2S_{(aq)} \to S_{(s)} + 2H^{+}_{(aq)} + 2Cl^{-}_{(aq)}$
The rate equation for this reaction is $\text{rate} = k[Cl_2][H_2S]$. Which of these mechanisms is/are consistent with this rate equation?
$A.$ $Cl_2 + H_2S \to H^{+} + Cl^{-} + Cl^{+} + HS^{-}$ (slow)
$Cl^{+} + HS^{-} \to H^{+} + Cl^{-} + S$ (fast)
$B.$ $H_2S \rightleftharpoons H^{+} + HS^{-}$ (fast equilibrium)
$Cl_2 + HS^{-} \to 2Cl^{-} + H^{+} + S$ (slow)

The most popularly known blood grouping is the $ABO$ grouping. It is named $ABO$ and not $ABC$,because '$O$' in it refers to having

$ABC$ is a triangular plate of uniform thickness. Its sides are as shown in the figure. If $I_{AB}$,$I_{BC}$,and $I_{CA}$ are the moments of inertia of the plate about axes $AB$,$BC$,and $CA$ respectively,then which of the following relations is correct?

$A$ capacitor $C = 100 \ \mu F$ is connected to three resistors,each of resistance $1 \ k\Omega$,and a battery of emf $9 \ V$. The switch $S$ has been closed for a long time to charge the capacitor. When switch $S$ is opened,the capacitor discharges with a time constant of.....$ms$.