$92 \ g$ of $NO_{2(g)}$ and $32 \ g$ of $O_{2(g)}$ are taken in a rigid container. At a constant temperature,they react to produce $N_2O_{5(g)}$. The pressure in the container after the reaction is observed to be $\frac{7}{8} P$,where $P$ is the initial pressure of the gaseous mixture. The percentage yield of the reaction is ....$\%$

Phosphoric acid is prepared commercially from phosphate ore as follows:
$Ca_3(PO_4)_2 + 3SiO_2 + 5C + 5O_2 + 3H_2O \to 3CaSiO_3 + 5CO_2 + 2H_3PO_4$
If $1.0 \ kg$ each of calcium phosphate and silica are used with an excess of $C$,$O_2$,and $H_2O$,what is the maximum quantity of phosphoric acid that can be produced (in $kg$)? (Atomic masses: $Ca = 40, P = 31, Si = 28, O = 16, H = 1$)

One mole of $Cl_{2(g)}$ was passed into $2 \text{ L}$ of cold $2 \text{ M}$ $KOH$ solution. After the reaction, the concentrations of $Cl^{-}$, $ClO^{-}$ and $OH^{-}$ are respectively (assume volume remains constant):

In the reaction $2P_2O_5 + 2HNO_3 \to P_4O_{10} + X$,what is the product $X$?

$5 \ mL$ of $0.1 \ M \ Pb(NO_{3})_{2}$ is mixed with $10 \ mL$ of $0.02 \ M \ KI$. The amount of $PbI_{2}$ precipitated will be about

When copper is reacted with a certain concentration of nitric acid,nitric oxide and nitrogen dioxide are produced in equal volumes according to the following reaction:
$xCu + yHNO_3 \to xCu(NO_3)_2 + NO + NO_2 + 3H_2O$
What are the stoichiometric coefficients $x$ and $y$?