Given below are two statements: Statement I: trans -But-2-ene upon...

Reaction of trans-but-2-ene with Br$_2$ in CCl$_4$ proceeds via anti-addition to give meso-2,3-dibromobutane.

In the Newman projection given in Statement I, the front carbon has Br at $0^{\circ}$, Me at $120^{\circ}$, and H at $240^{\circ}$. The back carbon has Br at $180^{\circ}$, Me at $60^{\circ}$, and H at $300^{\circ}$. For this staggered conformation to be meso, it must have a center of inversion, meaning a group at angle $\theta$ on the front carbon must have an identical group at $\theta + 180^{\circ}$ on the back carbon. While the Br atoms are opposite ($0^{\circ}$ and $180^{\circ}$), the front Me at $120^{\circ}$ is not opposite to the back Me at $60^{\circ}$. Thus, it lacks a center of inversion and represents a chiral enantiomer. Hence, Statement I is incorrect.

Reaction of cis-but-2-ene with alkaline KMnO$_4$ proceeds via syn-addition to give meso-butane-2,3-diol.

In the Newman projection given in Statement II, the front carbon has OH at $0^{\circ}$, Me at $120^{\circ}$, and H at $240^{\circ}$. The back carbon has OH at $60^{\circ}$, Me at $180^{\circ}$, and H at $300^{\circ}$. Rotating the back carbon by $60^{\circ}$ counter-clockwise perfectly eclipses all identical groups (OH with OH at $0^{\circ}$, Me with Me at $120^{\circ}$, H with H at $240^{\circ}$). This indicates the presence of a plane of symmetry, confirming it is the meso isomer. Hence, Statement II is correct.

Therefore, Statement I is incorrect but Statement II is correct.

Answer: Statement I is incorrect but Statement II is correct