Pure carbon is completely burnt in oxygen. The flue gas analysis is 70%CO2, 20%CO and 10%O2. The percent excess oxygen used is __________________?

Related Mcqs:

1. A sample of natural gas containing 80% methane (CH4) and rest nitrogen (N2) is burnt with 20% excess air. With 80% of the combustibles producing CO2 and the remainder going to CO, the Orsat analysis in volume percent is_________________?

   A. CO2 : 6.26, CO : 1.56, O2 : 3.91, H2O :15.66, N2 : 72.60
   B. CO2 : 7.42, CO : 1.86, O2 : 4.64, N2:86.02
   C. CO2 : 6.39, CO : 1.60, O2 : 3.99, H2O:25.96, N2:72.06
   D. CO2 : 7.60, CO : 1.90, O2 : 4.75, N2 : 85.74

2. A liquid/gaseous fuel containing hydrocarbons and high amount of sulphur is burnt with 40% excess air. The flue gas still contains large amount of carbon monoxide. This may be due to the_________________?

   A. Presence of large quantity of hydrogen in the fuel
   B. Low calorific value of the fuel
   C. High sulphur content in the fuel
   D. Lack of thorough mixing of fuel with air

3. A fuel containing carbon and carbon monoxide (but containing no hydrogen or its compounds) is burnt in pure oxygen at constant pressure. Its gross calorific value as compared to net calorific value will be_________________?

   A. More
   B. Less
   C. Same
   D. Data insufficient; can’t be predicted

4. Explosion limit of blast furnace gas is 37 to 71% gas in gas-air mixture. It means that the blast furnace gas will explode when burnt in a confined space, if its concentration in the gas-air mixture is _______________ percent?

   A. 71%
   C. In between 37 & 71%
   D. None of these

5. Oxygen content in a flue gas was found to be 4%. It implies that excess air used for combustion was around ______________ percent?

   A. 4
   B. 96
   C. 20
   D. 40

6. A carbonaceous fuel (containing no H2 or hydrocarbons) is burnt and the resulting flue gas contains 21% CO2. It means that___________________?

   A. 21% excess air has been used for combustion
   B. 21% excess oxygen has been used for combustion
   C. Complete combustion of fuel has taken place
   D. No excess air has been used for combustion

7. In flue gas analysis by Orsat’s apparatus, oxygen is absorbed by____________________?

   A. Potassium hydroxide
   B. Cuprous chloride
   C. Alkaline pyrogallol solution
   D. None of these

8. Flue gas obtained on complete combustion of pure acetylene (a hydrocarbon fuel) will contain __________________?

   A. CO
   B. CO2
   C. H2O
   D. Both B. & C.

9. In flue gas analysis by Orsat’s apparatus, carbon monoxide is absorbed by__________________?

   A. Cuprous chloride
   B. Potassium hydroxide
   C. Alkaline pyrogallol solution
   D. None of these

10. In flue gas analysis by Orsat’s apparatus, carbon dioxide is absorbed by______________________?

    A. Potassium hydroxide
    B. Dilute potassium carbonate
    C. Cuprous chloride
    D. Alkaline pyrogallol solution