Among the following statements,the incorrect statement is:

Match List-$I$ and List-$II$ :

List-$I$	List-$II$
$(a).$ Haematite	$(i).$ $Al_{2}O_{3} \cdot xH_{2}O$
$(b).$ Bauxite	$(ii).$ $Fe_{2}O_{3}$
$(c).$ Magnetite	$(iii).$ $CuCO_{3} \cdot Cu(OH)_{2}$
$(d).$ Malachite	$(iv).$ $Fe_{3}O_{4}$

Choose the correct answer from the options given below :

The ore pitchblende is the main source of

$ACl_2$ (excess) + $BCl_2$ $\rightarrow$ $ACl_4$ + $B \downarrow$
$BO \xrightarrow[\Delta]{> 400 \ ^oC} \frac{1}{2} O_2 + B$
If $A$ and $B$ are metals,then the ore of $B$ would be:

Metals are usually not found as nitrates in their ores. Out of the following two ($I$ and $II$) reasons,which is/are true for the above observation?
$I.$ Metal nitrates are highly unstable.
$II.$ Metal nitrates are highly soluble in water.

What percentage of the Earth's crust by mass is composed of oxygen (in $\%$)?