Question

Consider the following reactions
I. $N{a}_2{S}_2{O}_3+dil.HCl\stackrel{\Delta }{\to }$
II. $N{a}_2{S}_2{O}_3+C{l}_{2}water\stackrel{\Delta }{\to }$
III. $S{O}_2+2H_{2}S\stackrel{\Delta }{\to }$
IV. $H_{2}S+H_2{O}_2\stackrel{\Delta }{\to }$
The reactions which gives yellow turbidity are :

• A. II, III, and IV
• B. III and IV only
• C. I, III, and IV
• D. I, II, III, and IV

Answer 1

Answer: (D)

I, II, III, and IV

I. $N{a}_2{S}_2{O}_3+dil.HCl\stackrel{\Delta }{\to }NaCl+H_{2}O+S{O}_2\uparrow$
II. $N{a}_2{S}_2{O}_3+C{l}_{2}water\stackrel{\Delta }{\to }N{a}_{2}S{O}_4+HCl+S$
III. $S{O}_2+2H_{2}S\stackrel{\Delta }{\to }2H_{2}O+3S$
IV. $H_{2}S+H_2{O}_2\stackrel{\Delta }{\to }S{O}_3+5H_{2}O$
Hydrogen peroxide is a strong oxidizing agent. So the sulfur in hydrogen sulfide becomes oxidized to the max and the result is sulfur trioxide.