Multiple choice

200 ml of a gaseous mixture containing $\displaystyle :CO, CO_{2}$ and $N_{2}$ on complete combustion in just sufficient amount of $O_{2}$ showed contraction of 40 ml. When the resulting gases were passed through KOH solution it reduces by 50% then calculate the volume ratio of $\displaystyle :V_{co_{2}}:V_{co}:V_{N_{2}}$ in orginial mixture.

  1. 4 : 1: 5

  2. 2 : 3: 5

  3. 1 : 4: 5

  4. 1 : 3: 5
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C Correct answer
Explanation

Combustion of CO produces CO2, while CO2 remains unchanged. The contraction of 40 ml corresponds to the volume of O2 consumed (V_CO/2). The KOH treatment removes all CO2. Solving the stoichiometry leads to the ratio 1:4:5.

AI explanation

Assume the original 200 ml mixture contains 5z ml of CO2, 20z ml of CO, and 75z ml of N2 to match the format of the ratio options. During combustion, CO turns into CO2 according to 2CO + O2 -> 2CO2. By Gay-Lussac's law, 20z ml of CO reacts with 10z ml of O2 to form 20z ml of CO2, creating a volume contraction of exactly the oxygen used (10z). This contraction equals 40 ml, meaning z is 4. The original mixture contains 20 ml of CO2, 80 ml of CO, and 100 ml of N2. This results in the volume ratio of CO2 to CO to N2 as 1 : 4 : 5.

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