A copper ore containing $20\%$ Cu$2$S$,40\%$ FeS$2,30\%$ SiO$2$ and $10\%$ H$2$O is roasted by using fuel oil whose

weight is equal to $5\%$ of the ore weight. Exhaust gases formed as a result of combustion process are mixed

with the product gas of the roasting reaction and discharged as flue gases. Sulfur exhausts as sulfur dioxide

and discharged in flue gases. The products of roasting reaction are CuO, Fe$2$O$3$ and SiO$2.$ Roasting and

combustion reactions are realized using $100\%$ excess air. The fuel contains $85\%$ C and $15\%$ H$.$

Calculate

a$)$ Amount of the air $($m$3$

$)$ used per $1$ ton ore,

b$)$ Weight of the roasted ore,

c$)$ Amount of H$2$O $($in grams$)$ present in flue gases per m$3$