Which element exists in the free state mainly?

Sulphide ion is a soft base and its ores are common for metals. Which of the following metals commonly occur as sulphide ores?
$(a)$ $Pb$ $(b)$ $Al$ $(c)$ $Ag$ $(d)$ $Mg$
Choose the correct answer from the options given below:

Match the following ores with their compositions:

$A$. Calamine	$i$. $CuFeS_2$
$B$. Chalcopyrite	$ii$. $ZnCO_3$
$C$. Bauxite	$iii$. $Fe_2O_3$
$D$. Haematite	$iv$. $Al_2O_3 \cdot 2H_2O$

Match the following List-$I$ (Name of the mineral) with List-$II$ (Type):
| List-$I$ | List-$II$ |
| :--- | :--- |
| $A$. Calamine | $I$. Sulphide |
| $B$. Bauxite | $II$. Halide |
| $C$. Kaolinite | $III$. Carbonate |
| $D$. Cryolite | $IV$. Oxide |
| | $V$. Silicate |

Match List-$I$ with List-$II$.

List-$I$ (Ore)	List-$II$ (Element Present)
$a$. Kernite	$i$. Tin
$b$. Cassiterite	$ii$. Boron
$c$. Calamine	$iii$. Fluorine
$d$. Cryolite	$iv$. Zinc

Choose the most appropriate answer from the options given below.

The composition of siderite ore is: