The weight of calcium oxide formed by burning $20 \ g$ of calcium in excess oxygen is $.... \ g$

The yield of each step as actually carried out in the laboratory is given in the reaction scheme below. Calculate the overall percentage yield of the reaction.
$Me_3C-CO-CH_3$ $\xrightarrow{58\% (A)} Me_3C-CO-CH_2Br$ $\xrightarrow{54\% (B)} Me_3C-CH(OH)-CH_2Br$ $\xrightarrow{68\% (C)} Me_3C-CH(O)CH_2$

$0.1 \ M$ solution of $KI$ reacts with excess of $H_2SO_4$ and $KIO_3$ solution. According to the equation $5I^{-} + IO_3^{-} + 6H^{+} \rightarrow 3I_2 + 3H_2O$. Identify the correct statements $:$
$(A)$ $200 \ mL$ of $KI$ solution reacts with $0.004 \ mol$ of $KIO_3$.
$(B)$ $200 \ mL$ of $KI$ solution reacts with $0.006 \ mol$ of $H_2SO_4$.
$(C)$ $0.5 \ L$ of $KI$ solution produced $0.005 \ mol$ of $I_2$.
$(D)$ Equivalent weight of $KIO_3$ is equal to $\frac{\text{Molecular weight}}{5}$.
Choose the correct answer from the options given below $:$

Under the same conditions of temperature and pressure,the ratio of the masses of equal volumes of $O_2$,$O_3$,and $SO_2$ will be respectively .............

Mass of methane required to produce $22 \ g$ of $CO_2$ after complete combustion is . . . . . . $g.$ (Given Molar mass in $g \ mol^{-1}$: $C=12.0, H=1.0, O=16.0$)

Which of the following has the same molar concentration as a $2N$ $HCl$ solution?