Question

100 mL of a gaseous mixture containing $CO,C{O}_2$ and $O_2$ was sparked; there was contraction of 80 mL volume when the mixture was passed through aqueous caustic potash KOH. The composition of initial gaseous mixture will be respectively :

• A. 20 mL, 70 mL, 10 mL
• B. 50 mL, 30 mL, 20 mL
• C. 30 mL, 50 mL, 20 mL
• D. 30 mL, 60 mL, 10 mL

Answer 1

The correct option is D 30 mL, 60 mL, 10 mL

lets first see what happen when gaseous mixture containing CO ,$C{O}_2$ and $O_2$ was sparked and pass through KOH

i) CO react with $O_2$ to form $C{O}_2$

2CO +$O_2$$\to$2$C{O}_2$

ii) KOH absorb the $C{O}_2$

In option D ,

(i.e 30 mL CO, 60 mL $C{O}_2$ , 10 mL$O_2$)

20 mL of CO react with 10 mL of $O_2$ to form 20 mL of $C{O}_2$

but, as already 60 mL of $C{O}_2$ is present in mixture total amount of $C{O}_2$ will be 60+20= 80 mL

and thus, when passed through KOH this 80 mL of $C{O}_2$ will be absorbed

hence, there is 80 mL of volume contraction occur

so, option D is correct.