$$ \text { Match the following } $$

$$ \begin{array}{llll} \hline & \begin{array}{l} \text { List-I } \\ \text { (Sol) } \end{array} & & \begin{array}{c} \text { List-II } \\ \text { (Method of preparation) } \end{array} \\ \hline \text { (A) } & \mathrm{As}_2 \mathrm{~S}_3 & \text { I. } & \text { Bredig's arc method } \\ \hline \text { (B) } & \mathrm{Au} & \text { II. } & \text { Oxidation } \\ \hline \text { (C) } & \mathrm{S} & \text { III. } & \text { Hydrolysis } \\ \hline \text { (D) } & \mathrm{Fe}(\mathrm{OH})_3 & \text { IV. } & \text { Double decomposition } \\ \hline \end{array} $$

The correct answer is

Observe the following reactions

I. $\mathrm{N}_2(g)+3 \mathrm{H}_2(g) \xrightarrow[773 \mathrm{~K}, 200 \mathrm{~atm}]{x} 2 \mathrm{NH}_3(g)$

II. $\mathrm{CO}(\mathrm{g})+\mathrm{H}_2 \mathrm{O}(\mathrm{g}) \xrightarrow[673 \mathrm{~K}]{Y} \mathrm{CO}_2(\mathrm{~g})+\mathrm{H}_2(\mathrm{~g})$

III. $\mathrm{CH}_4(g)+\mathrm{H}_2 \mathrm{O}(g) \xrightarrow[1270 \mathrm{~K}]{\mathrm{z}} \mathrm{CO}(g)+3 \mathrm{H}_2(g)$

Catalysts $X, Y, Z$ respectively are

What is the indicator used in argentometric titrations?

In a Freundlich adsorption isotherm, if the slope is unity and $k$ is 0.1 , the extent of adsorption at 2 atm is ( $\log 2=0.30$ )