1. Calculate the weight and volume of air required for the complete combustion of 2kg of carbon.
a) weight of air=5000g; volume of the air=17000l
b) weight of air=17000g; volume of the air=15000l
c) weight of air=5330g; volume of the air=17766.66l
d) weight of air=8220g; volume of the air=1555.45l
Explanation: For calculation first the reaction is C+O2 → CO2.For this equation, 12 kg of c requires 32kg of oxygen for combustion then find for 2kg of carbon dioxide. At NTP 1g mole of oxygen occupies 22.4l then calculates for the weights of carbons that has calculated before then find volume of air by knowing that 100 parts of air contains 21 parts of oxygen.
2. The coal sample contains=80%; H=4%; O=2%; N=12%; S=2%, the remainder is ash and then calculate the volume of air required for perfect combustion of 1kg of fuel assuming STP conditions.
a) weight of oxygen required=10.65kg; volume of the oxygen=8725l
b) weight of oxygen required=11.25kg; volume of the oxygen=8500l
c) weight of oxygen required=11.25; volume of the oxygen=8200l
d) weight of oxygen required=10.65kg; volume of the oxygen=8166.6l
Explanation: The total weight of oxygen required for combustion is calculated by taking every component equation. It will be 2.45kg and then calculate the volume of oxygen. At STP conditions 32g of oxygen occupies 22.4l volume. Calculate for 2450g and then find weight of oxygen required as we know 100kg of gas requires 23kg of oxygen.
3. CO=40%, H2=12%, CO2=6%, CH2=2%, N2=50% are the components in the coal. What will be the composition of the dry flue gas, if the 50% excess air was used for burning 100m3 of gas?
a) CO2=14.9%, N2=80%, O2=5.2%
b) CO2=12.2%, N2=70.8%, O2=6.5%
c) CO2=14.9%, N2=79.9%, O2=5.2%
d) CO2=13%, N2=77%, O2=75
Explanation: Form a table formulating the actual components in 100m3, combination reactions and volume required and % of dry gas. Find total volume of gas. Later calculate the volume of oxygen in excess air by calculating the volume of dry products. Add the dry products combinations to get the total products combination and then calculate the carbon dioxide, nitrogen and oxygen percentages.
4. Which of the following releases less amount of carbon dioxide per unit of energy?
a) Coal
b) Oil
c) LPG
d) Petrol
Explanation: Oil releases very less amount of carbon dioxide when compared to coal, LPG and petrol but it also has very small calorific values when compared to those fuels and less efficient.
5. Which of the following is not the constitute of CNG?
a) Ethane
b) Propane
c) Isobutane
d) CO
Explanation: Isobutane is also called as LPG is not the constitute of the CNG. Ethane, propane and other gases like nitrogen, CO are the constituents of the CNG.
6. A high temperature lubricants used may undergo ________
a) vulcanization
b) volatilization
c) lubrication
d) combustion
Explanation: A high temperature lubricants used may undergo volatilization. The vulcanization is the process of rubber in presence of sulphur.
7. For heavy cutting, the effective lubricants are _________
a) coconut oils
b) cutting oils
c) kerosene
d) diesel
Explanation: The cutting oils are most suitable oils for heavy cutting. The lubricants contain the additives like fatty oils and sulphurized fatty oils and chlorinated compounds.
8. The reduction in friction is only when _________ of the oil film is __________ than that of the metal.
a) shear strength, more
b) shear strain, less
c) shear strain, more
d) shear strength, less
Explanation: The friction in friction is only when shear strength of the oil film must be less than the metal. This will reduce the electricity consumption.
9. The friction is needed to be reduced because _________
a) will increase the load
b) will increase the consumption electricity
c) it will be reducing the excess heat generation
d) will increase the excess the heat generation
Explanation: The friction is needed to be reduced because it will be reducing the excess heat generation which will improve the machine life period.
10. Oil emulsions are the most effective lubricants in _________
a) heavy cuttings
b) light cutting
c) engines
d) gears
Explanation: Oil emulsions are the most effective lubricants in light cuttings. The emulsions have less lubricating effects than that of cutting oils but cutting oils are good as cooling media.