Match the following columns:

Column-$I$	Column-$II$
$A$. Christmas tree	$i$. Bennettites
$B$. Fossil plant	$ii$. Cycas
$C$. Ornamental plant	$iii$. Araucaria
$D$. Tallest tree	$iv$. Sequoia
	$v$. Thuja

The metal ion present in vitamin $B_{12}$ is

The average degree of freedom per molecule of a gas is $6$. The gas performs $25 \, J$ of work while expanding at constant pressure. The heat absorbed by the gas is ...... $J$.

Arrange the following compounds in the decreasing order of their reactivity towards $HBr$:
$(a)$ $(CH_3)_2C=CH_2$
$(b)$ $CH_3O-C(CH_3)=CH_2$
$(c)$ $CH_3OCH_2-C(CH_3)=CH_2$

Bottles containing $C_6H_5I$ and $C_6H_5CH_2I$ lost their original labels. They were labelled $A$ and $B$ for testing. $A$ and $B$ were separately taken in a test tube and boiled with $NaOH$ solution. The end solution in each tube was made acidic with dilute $HNO_3$ and then some $AgNO_3$ solution was added. Substance $B$ gave a yellow precipitate. Which one of the following statements is true for this experiment?

From which plant is cocaine obtained?