The average molecular weight of a flue gas having the composition by volume as CO2 = 25%, O2 = 25%, N2 = 50% will be___________________?

Related Mcqs:

1. The calorific value of a gas of composition CO2 = 20%, H2 = 50%, CH4 = 30%, is y. If the composition of gas is changed to H2 = 50%, CH4 = 30%, CO2 = 10%, N2 = 10%, then the calorific value will be___________________?

   A. y
   B. 0.95 y
   C. 1.05 y
   D. 1.8 y

2. 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

3. The maximum percentage of CO2 in a flue gas (from a carbonaceous fuel) can be_________________?

   A. 21
   B. 77
   C. 79
   D. 29

4. 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 __________________?

   A. 20
   B. 12.5
   C. 0
   D. 10

5. 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

6. 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

7. C.V. (kcal/Nm3) of gaseous fuels _____________ with increase in molecular weight?

   A. Decreases
   B. Increases
   C. Remain constant
   D. May increase or decrease, depends on combustibles

8. Flue gas discharge velocity through chimney of a big thermal power plant may be around ________________ m/sec?

   A. 0.5
   B. 10
   C. 50
   D. 500

9. White flue gas (resembling steam) coming out of the chimney of a thermal power plant indicates that the fuel used in the boiler furnace is_________________?

   A. Tar
   B. Coke oven gas
   C. Pitch
   D. Pulverised coke

10. 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