Observe the oxides $CO, B_2O_3, SiO_2, CO_2, Al_2O_3, PbO_2, Tl_2O_3$. The number of acidic oxides in the list is:

Which of the following statements are correct?
$1.$ Charcoal can be obtained by heating wood in the absence of air.
$2.$ Charcoal is an impure form of graphite.
$3.$ Diamond is thermodynamically the most stable allotrope of carbon.
$4.$ Coke is used as an oxidising agent during the extraction of iron from its ores.

Which of the following are methanides?

Reaction of an inorganic sulphite $X$ with dilute $H_{2}SO_{4}$ generates compound $Y$. Reaction of $Y$ with $NaOH$ gives $X$. Further,the reaction of $X$ with $Y$ and water affords compound $Z$. $Y$ and $Z$,respectively,are:

$SiCl_4$ on hydrolysis gives:

$(a)$ Classify the following oxides as neutral,acidic,basic,or amphoteric:
$CO, B_2O_3, SiO_2, CO_2, Al_2O_3, PbO_2, Tl_2O_3$
$(b)$ Write suitable chemical equations to show their nature.