Engineering Questions with Answers - Multiple Choice Questions

Applied Chemistry MCQ – Cracking and Knocking of Petroleum

1 - Question

Octane number is a rating of ___________
a) petrol knocking
b) diesel knocking
c) petrol cracking
d) diesel cracking

View Answer

Answer: a
Explanation: Octane number is the rating for petrol knocking and cetane number is the rating for diesel knocking.




2 - Question

Which of the following element has 100% anti knocking?
a) 2-methyl naphthalene
b) heptadecane
c) CH3-(-CH2-)14-CH3
d) 3-methyl naphthalene

View Answer

Answer: c
Explanation: CH3-(-CH2-)14-CH3 has the 100% anti knocking value. It is also called as n-hexa decane. The lowest anti knocking value that is 0 is for the element 2-methyl naphthalene.




3 - Question

To improve anti knock of diesel ___________ are added.
a) TEL
b) Pre-ignition dopes
c) Di ethyl telluride
d) N-hexa decane

View Answer

Answer: b
Explanation: To improve the anti-knock of diesel the pre-ignition dopes are added. Generally ethyl nitrate, isoamyl nitrate and acetane peroxide are added as pre-ignition dopes.




4 - Question

What are the best anti knocking reagents of petrol?
a) straight chain alkanes
b) straight chain alkenes
c) alkynes
d) aromatics

View Answer

Answer: d
Explanation: The straight chain compounds cause maximum petrol knock and aromatics are called the best anti knock agents of petrol.




5 - Question

Pre-ignition of the fuel is seen in _________
a) petrol knocking
b) petrol cracking
c) diesel cracking
d) diesel knocking

View Answer

Answer: a
Explanation: Petrol knocking is due to the pre-ignition of the fuel and in diesel knocking is because of ignition-lag of the fuel.




6 - Question

In liquid phase thermal cracking, the yield of petrol is ________
a) 50%-60%
b) 60%-70%
c) 70%-80%
d) 80%-90%

View Answer

Answer: a
Explanation: In liquid phase catalytic cracking, the yield of petrol is 50-60% with good octane rating of 65-70. Here, the cracked products are sent through fractionating where the products are separated.




7 - Question

Knocking is also called as __________
a) cracking
b) pinging
c) doping
d) crushing

View Answer

Answer: b
Explanation: Pinging is the other name of knocking. Cracking means the process of breaking the higher hydrocarbons into simple atoms. Doping means adding impurity to a pure metal to improve its conductivity. Crushing means divided into small pieces.




8 - Question

 In the catalytic cracking, what Is the catalyst used?
a) Nacl
b) Kcl
c) ZnSO4
d) Al2O3

View Answer

Answer: d
Explanation: Al2O3 and also Al2(SiO3)3 acts as catalysts in catalytic cracking. Usage of these catalysts, the quality of petrol is high without any heating.




9 - Question

Which of the following order of petrol knocking is true?
a) aromatics > branched paraffins > olefins > cyclo paraffins > aromatics
b) straight chain paraffins > olefins > branched paraffins > cyclo paraffins > straight chain paraffins
c) straight chain paraffins > branched paraffins > olefins > cyclo paraffins > aromatics
d) straight chain paraffins > branched paraffins > olefins > aromatics > cyclo paraffins

View Answer

Answer: c
Explanation: The order of petrol knocking is given by straight chain paraffins > branched paraffins > olefins>cyclo paraffins > aromatics. As we know that aromatics are the best anti knock agents so, the petrol knock for them is very low.




10 - Question

In fixed bed catalytic cracking, the catalyst is reactivated after every __________
a) 8-10hrs
b) 20-24hrs
c) 5-7hrs
d) 12-15hrs

View Answer

Answer: a
Explanation: In fixed-bed catalytic cracking, the catalyst is reactivated after every 8-10hrs and continuous by burning the deposited carbon.




11 - Question

 In vapour phase thermal cracking, the temperature achieved is ___________
a) 200-400oC
b) 600-650oC
c) 500-820oC
d) 700-800oC

View Answer

Answer: b
Explanation: In vapour phase thermal cracking, the temperature achieved is 600-650oC and in fixed-bed catalytic cracking, the temperature is about 425-250oC.




12 - Question

In moving bed catalytic cracking, the catalyst is in the form of ____________
a) fine powder
b) pallets
c) liquid form
d) gaseous form

View Answer

Answer: a
Explanation: In moving bed catalytic cracking, the catalyst is made into a fine powder and charged into the catalyst chamber. So, they move freely like fluids.




13 - Question

The gasoline vapours are purified by __________
a) thermal cracking
b) catalytic cracking
c) stabilization
d) knocking

View Answer

Answer: c
Explanation: The stabilization is the process in which the gasoline vapours are purified. Thermal cracking and catalytic cracking are the processes to purify the petrol.




14 - Question

 The pressure applied in vapour phase cracking is __________
a) 10-20kg/cm2
b) 100kg/cm2
c) 50kg/cm2
d) 80kg/cm2

View Answer

Answer: a
Explanation: The pressure applied in the vapour phase cracking is very small about 10-20kg/cm2.The oils will be very easily vaporized.




15 - Question

The pressure applied in fixed-bed catalytic cracking is __________
a) 10kg/cm2
b) 50kg/cm2
c) 100kg/cm2
d) 1.5kg/cm2

View Answer

Answer: d
Explanation: The pressure of 1.5kg/cm2 applied in the fixed bed catalytic cracking and during this process 40% of charge is converted into gasoline.

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