Identify the catalyst (A) used in following reaction.

$$\mathrm{CO}+\mathrm{H}_2 \mathrm{O} \stackrel{\mathrm{A}}{\rightleftharpoons} \mathrm{CO}_2+\mathrm{H}_2$$

What is value of PV type of work for following reaction at 1 bar?

$$\underset{(200 \mathrm{~mL})}{\mathrm{C}_2 \mathrm{H}_{4(\mathrm{~g})}}+\underset{(150 \mathrm{~mL})}{\mathrm{HCl}_{(\mathrm{g})}} \longrightarrow \mathrm{C}_2 \mathrm{H}_5 \mathrm{Cl}_{(\mathrm{g})}$$

$$\int\limits_0^\pi \frac{d x}{4+3 \cos x}=$$

If $$y=\log _{\sin x} \tan x$$, then $$\left(\frac{\mathrm{d} y}{\mathrm{~d} x}\right)_{x=\frac{\pi}{4}}$$ has the value