Fuels and Combustion
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 reminder going to CO, the Orsat analysis in volume percent is

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

ANSWER DOWNLOAD EXAMIANS APP

Fuels and Combustion
Low temperature carbonisation

Is meant for the production of 'metallurgical coke'
Produces higher quantity of gas than high temperature carbonisation
Is mainly for producing the smokeless domestic coke
Produces less quantity of tar than high temperature carbonisation

ANSWER DOWNLOAD EXAMIANS APP

Fuels and Combustion
A coal having high ratio of volatile matter to fixed carbon as compared to a coal having low ratio of volatile matter to fixed carbon

None of these
Is more difficult to ignite and produces a shorter flame
Is less liable to spontaneous combustion on storage
Requires smaller combustion space and less secondary air

ANSWER DOWNLOAD EXAMIANS APP

Fuels and Combustion
Ratio of primary air to secondary air increases with increase in the rank of coal, because the

Ratio of fixed carbon to volatile matter increases
High rank coals have higher amount of volatile matter
Oxygen content progressively decreases
Calorific value of the coal increases

ANSWER DOWNLOAD EXAMIANS APP