A cube of edge length 1 cm is divided into smaller cubes of uniform size of length 1 nm . Assuming that, no voids are present, the ratio of total surface area of all the cubes of 1 nm edge length to the surface area of the initial cube is

Catalysts in the following reactions are

(I) $\mathrm{CH}_3 \mathrm{COOCH}_3(l)+\mathrm{H}_2 \mathrm{O}(l)\longrightarrow \mathrm{CH}_3 \mathrm{COOH}(a q)+\mathrm{CH}_3 \mathrm{OH}(l)$

(II) $2 \mathrm{SO}_2(\mathrm{~g}) \longrightarrow 2 \mathrm{SO}_3(\mathrm{~g})$

(III) $2 \mathrm{SO}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \longrightarrow 2 \mathrm{SO}_3(\mathrm{~g})$

(IV) $\mathrm{N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g}) \longrightarrow 2 \mathrm{NH}_3(\mathrm{~g})$

For $\mathrm{As}_2 \mathrm{~S}_3$ sol, the most effective coagulating agent is

Which of the following is true for spontaneous adsorption?