Question

100 ml mixture of Co and $C{O}_2$ is mixed with 30 ml of oxygen and sparked in a eudiometer tube. The residual gas after treatment with aqueous KOH has a volume of 10 ml which remains unchanged when treated with alkaline pyrogallol. If all the volumes are under the same conditions, point out the correct option(s).

• A. The volume of CO that reacts, is 60 ml
• B. The volume of CO that remains unreacted, is 10 ml
• C. The volume of $O_2$ that remains unreacted, is 10 ml
• D. The volume of $C{O}_2$ that gets absorbed by aqueous KOH, is 90 ml

Answer 1

Answer: (A), (B), (D)

The volume of $C{O}_2$ that gets absorbed by aqueous KOH, is 90 ml

$2CO+O_2\to 2C{O}_2$ The residual gas is CO.
Volume of CO oxidised $=2\times 30=60ml$; Volume of CO = 60 + 10 = 70 ml
Volume of $C{O}_2$ formed = 60 ml; Volume of $C{O}_2$ absorbed by KOH = 3 + 60 = 90 ml