Fuels and Combustion
Ignition temperature decreases progressively from anthracite to lignite, because

Carbon content decreases
Ash content increases
Moisture content increases
Volatile matter content increases

ANSWER DOWNLOAD EXAMIANS APP

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

ANSWER DOWNLOAD EXAMIANS APP