Acidified $K_2Cr_2O_7$ solution turns green when $Na_2SO_3$ is added to it. This is due to the formation of

$A$ sample $(5.6 \ g)$ containing iron is completely dissolved in cold dilute $HCl$ to prepare $250 \ mL$ of solution. Titration of $25.0 \ mL$ of this solution requires $12.5 \ mL$ of $0.03 \ M \ KMnO_4$ solution to reach the end point. The number of moles of $Fe^{2+}$ present in the $250 \ mL$ solution is $x \times 10^{-2}$ (consider complete dissolution of $FeCl_2$). The amount of iron present in the sample is $y \%$ by weight. (Assume: $KMnO_4$ reacts only with $Fe^{2+}$ in the solution. Use: Molar mass of iron as $56 \ g \ mol^{-1}$)
$(1)$ The value of $x$ is. . . . .
$(2)$ The value of $y$ is. . . . .

Which of the following is not correct?

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$FeCl_3 + Na_3PO_4 \longrightarrow FePO_4 \downarrow + 3NaCl$

$O_3 + 2KI_{(aq)} \rightarrow ?$ The product of the reaction is:

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$Ca(OH)_2 + CO_2 \longrightarrow CaCO_3 \downarrow + H_2O$