The compound formed by passing ethylene gas into a cold alkaline solution of $KMnO_4$ is:

What is the major product obtained from the debromination of meso-$2,3$-dibromobutane?

Baeyer's reagent is used in the laboratory for

Predict the major product for the following reaction:
$Cyclopentyl-ethene \xrightarrow[(ii) H_2O_2, NaOH]{(i) B_2H_6(THF)} ?$

Rank the following alkenes in order of decreasing heats of hydrogenation (largest first):
$1$. $1-$butene
$2$. $2-$methyl$-2-$butene
$3$. trans$-2-$butene
$4$. cis$-2-$butene

Predict the major product $A$ for the following reaction:
$2\text{-methylbuta-1,3-diene} + HBr (1 \text{ eq.}) \xrightarrow{-80^{\circ}C (1,2\text{-addition})} A$