# Farm Tractor Questions and Answers – Fuels Combustion

This set of Farm Tractor Multiple Choice Questions & Answers (MCQs) focuses on “Fuels Combustion”.

1. Liquid fuels are advantageous than solid fuels.
a) True
b) False

Explanation: Liquid fuels are generally used in all the internal combustion engines. They have higher calorific value compared to solid fuels. They are preferred due to a minimum storage space, no ash and no – deterioration.

2. Which term is denoted as the energy liberated by a fuel while it is undergoing complete combustion under standard conditions?
a) Heat energy
b) Calorific value
c) Combustion value
d) Fuel value

Explanation: Calorific value is also called as heating value of a fuel. The unit for calorific value is KJ/Kg or KJ/m3. If the reactant has hydrogen, there will be the formation of H2O. Depending on its state, there are two values net and gross calorific values. The calorific value of diesel is 45,500 KJ/Kg.

3. Find the stoichiometric air/fuel ratio for complete combustion of ethanol.
a) 9:1
b) 10:1
c) 1:9
d) 8:1

Explanation: C2H5OH + 3O2 🡢 2CO2 + 3H2O
Calculating molecular mass
2C = (2 * 12 = 24) + (6H = 6 * 1 = 6) + (O = 1 * 16 = 16) = 46 Kg/mole
6O = 6 * 16 = 96 Kg/mole
For combustion oxygen required = 96/46 = 2.086 Kg/mole
= 2.086/0.23 = 9.07 = 9/1 (0.23 is for mass percentage of oxygen in air)
Air/fuel ratio = 9:1

4. Scavenging is the process of expelling exhaust gases.
a) False
b) True

Explanation: Scavenging is the process of removing the exhaust gases and other burnt compounds from the cylinder in order to intake of fresh air for next cycle. If the gases present in the cylinder, it can cause incomplete combustion.

5. In which engine auto – ignition takes place?
a) Steam engine
b) Diesel engine
c) Petrol engine
d) External combustion engine

Explanation: The ignition of a diesel engine is done by the high temperature of the air. At the end of the compression stroke, the fuel is injected in the atomized form which rapidly gets ignited due to higher pressure and temperature.

6. What is known as the amount of fuel consumed per unit power?
a) Specific fuel consumption
b) Fuel consumption
c) Fuel flow rate
d) Specific output

Explanation: It is the ratio of the amount of fuel combusted to the amount of power produced by an engine. It is measured in Kg/Kwh. If the fuel consumption is low for respective power production i.e. specific fuel consumption is low, it will have higher efficiency.

7. What is called as the ratio of the mass flow rate of fuel to the brake power?
a) Brake specific fuel consumption
b) Indicated specific fuel consumption
c) Specific fuel consumption
d) Specific output

Explanation: The brake power is the power developed in the crankshaft of an engine. Its unit is Kg/Kwh. The indicated specific fuel consumption is the ratio of the mass flow rate of the fuel to the indicated power. Indicated power is the power produced by the combustion of fuel in the combustion chamber.

8. Which is the correct sequence of the fuel system in the tractor engine?
a) Fuel tank 🡢 10 filter 🡢 20 filter 🡢 fuel pump
b) Fuel pump 🡢 20 filter 🡢 10 filter 🡢 fuel tank
c) 10 filter 🡢 20 filter 🡢 fuel pump 🡢 fuel tank
d) Fuel tank 🡢 fuel pump 🡢 10 filter 🡢 20 filter

Explanation: Fuel from the tank can flow to the injector through filters. The flow will be a gravity flow and there is a fuel lift pump accordingly. The primary filter removes water and other dirt, while the secondary filter removes fine particles. The filter medium will be woven cloth, paper etc.

9. What is the purpose of the carburettor in a spark – ignition engine?
a) Atomizing of fuel
b) Atomizing and mixing of fuel with air
c) Increasing velocity of air
d) Decreasing the velocity of air

Explanation: The carburettor is a device for atomizing the fuel and mixing it with the air in an optimum proportion. The process is called as carburetion. In a spark – ignition engine, the air – fuel mixture is prepared separately and then entered into the cylinder. There will be a spark plug for ignition.

10. Which device is used to inject the fuel into the cylinder?
a) Injector
b) Carburettor
c) Nozzle
d) Pump

Explanation: Fuel is injected in the cylinder during the end of the compression stroke. It is sprayed into the cylinder in the form of fine particles at higher pressure. Some modern tractors have multiple holes in the injectors. Each cylinder is fitted with the individual fuel injector.

Sanfoundry Global Education & Learning Series – Farm Tractor.

To practice all areas of Farm Tractor, here is complete set of Multiple Choice Questions and Answers.

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