Which of the following pairs of $2,3$-butanediol are enantiomeric?

Two particles $A$ and $B$,initially at rest,move towards each other under a mutual force of attraction. At an instance when the speed of $A$ is $v$ and the speed of $B$ is $2v$,the speed of the centre of mass $(CM)$ is:

When $X$ amperes of current is passed through molten $AlCl_3$ for $96.5 \ s$,$0.09 \ g$ of aluminium is deposited. What is the value of $X$?

An inductance of $\frac{200}{\pi} \ mH$,a capacitance of $\frac{10^{-3}}{\pi} \ F$ and a resistance of $10 \ \Omega$ are connected in series with an $AC$ source of $220 \ V, 50 \ Hz$. The phase angle of the circuit is:

$A$ particle moves in a circle of radius $25 \, cm$ at two revolutions per second. The acceleration of the particle in $m/s^2$ is

Among the following series of transition metal ions,the one where all metal ions have $3d^2$ electronic configuration is