Which of the following ions is the strongest oxidizing agent? (Atomic Number of $\mathrm{Ce}=58, \mathrm{Eu}=63, \mathrm{~Tb}=65, \mathrm{Lu}=71$)

$37.8 \mathrm{~g} \mathrm{~N}_2 \mathrm{O}_5$ was taken in a 1 L reaction vessel and allowed to undergo the following reaction at 500 K

$$2 \mathrm{~N}_2 \mathrm{O}_{5(\mathrm{~g})} \rightleftharpoons 2 \mathrm{~N}_2 \mathrm{O}_{4(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})}$$

The total pressure at equilibrium was found to be 18.65 bar.

Then, $\mathrm{Kp}=$ _________ $\times 10^{-2}$ [nearest integer]

Assume $\mathrm{N}_2 \mathrm{O}_5$ to behave ideally under these conditions.

Given: $\mathrm{R}=0.082$ bar $\mathrm{L} \mathrm{mol}^{-1} \mathrm{~K}^{-1}$

Among the following cations, the number of cations which will give characteristic precipitate in their identification tests with $\mathrm{K}_4\left[\mathrm{Fe}(\mathrm{CN})_6\right]$ is ________.

$$\mathrm{Cu}^{2+}, \mathrm{Fe}^{3+}, \mathrm{Ba}^{2+}, \mathrm{Ca}^{2+}, \mathrm{NH}_4^{+}, \mathrm{Mg}^{2+}, \mathrm{Zn}^{2+}$$

Consider the following reaction occurring in the blast furnace:

$$\mathrm{Fe}_3 \mathrm{O}_{4(\mathrm{~s})}+4 \mathrm{CO}_{(\mathrm{g})} \rightarrow 3 \mathrm{Fe}_{(\mathrm{l})}+4 \mathrm{CO}_{2(\mathrm{~g})}$$

' $x$ ' kg of iron is produced when $2.32 \times 10^3 \mathrm{~kg} \mathrm{Fe}_3 \mathrm{O}_4$ and $2.8 \times 10^2 \mathrm{~kg} \mathrm{CO}$ are brought together in the furnace. The value of ' $x$ ' is _________ . (nearest integer)

{Given: molar mass of $\mathrm{Fe}_3 \mathrm{O}_4=232 \mathrm{~g} \mathrm{~mol}^{-1}$

molar mass of $\mathrm{CO}=28 \mathrm{~g} \mathrm{~mol}^{-1}$

molar mass of $\mathrm{Fe}=56 \mathrm{~g} \mathrm{~mol}^{-1}$}