250+ TOP MCQs on Natural Products – Petroleum and Answers

Chemical Process Technology Questions & Answers for Exams on “Natural Products – Petroleum”.

1. Which of the following unit operation is based on difference in freezing point?
a) Adsorption
b) Extraction
c) Crystallization
d) Distillation

Answer: c
Clarification: All are physical changes or unit operations used in petroleum refinery process. Unit operation crystallization is based on difference in freezing point difference. Wax preparation process uses crystallization method.

2. Which of the following relation between driving force and unit operation is correct?
a) Crystallization – relative solubility in different solvents
b) Extraction – relative volatilities
c) Absorption – freezing point difference
d) Adsorption – relative adherence

Answer: d
Clarification: The general driving force for any unit operation is concentration gradient or more precisely chemical potential. The correct option is that adsorption is based on relative adherence.

3. Which one of the following is a wrong statement?
a) Pressure and temperature requirements are higher for catalytic cracking
b) Rate of polymerization is increased by increasing pressure
c) Thermal pyrolysis of methane and ethane require quenching
d) Higher the molecular weight, higher is the coking tendency

Answer: a
Clarification: The statement is wrong as pressure and temperature requirements are lower for catalytic cracking. Gas oil undergoes catalytic cracking to produce high yield of petrol fraction.

4. Match the following?

Feed (thermal pyrolysis)                   Process
i. Methane                            A. coking
ii. Ethane                            B. Acetylene production
iii. Residual crude                   C. Ethylene production

a) i-A, ii-B, iii-C
b) i-B, ii-C, iii-A
c) i-C, ii-B, iii-A
d) i-B, ii-A, iii-C

Answer: b
Clarification: As thermal pyrolysis of methane and ethane produce acetylene and ethylene, hence the processes are known as acetylene production, ethylene production etc. Thermal pyrolysis of residual crude process is called coking.

5. Which catalyst doesn’t have high tolerance towards S when it is reactivated with steam in catalytic cracking process?
a) Iron
b) Chromium
c) Copper
d) Nickel

Answer: b
Clarification: Chromium doesn’t have high tolerance towards S when it is reactivated with steam in catalytic cracking process. Catalyst must be selected in such a way that it is not poisoned by metals.

6. Increase in pressure during catalytic cracking process ____________ octane number.
a) Decreases
b) Increases
c) Doesn’t effect
d) Remains same

Answer: a
Clarification: Increase in pressure during catalytic cracking process; decreases unsaturation and hence octane number decreases, which results in increase in coke production though reactor throughput also increases.

7. Which of the following is not a distinctive feature of catalytic cracking process?
a) Less polymerization
b) High quality petrol
c) Less coke production
d) Less Isomerization

Answer: d
Clarification: Distinctive features of catalytic cracking process are high quality products, selective cracking, less light ends, more Isomerization, less polymerization, and little coke.

8. Thermodynamically dehydrogenation reactions are favorable at ___________
a) High temperature, low pressure
b) Low temperature, high pressure
c) High temperature, high pressure
d) Low temperature, low pressure

Answer: a
Clarification: Thermodynamically dehydrogenation reactions are favorable at High temperature and low pressure. Hydro cracking and carbon deposition can occur at high temperature, hence high hydrogen pressures are used to reduce them.

9. Which of the following statement is wrong regarding Catalytic reformates?
a) They contain no olefins
b) They are resistant to oxidation
c) They have low sulfur and gum content
d) They are low in octane number

Answer: d
Clarification: Catalytic reformates contains no olefins, forms blending stocks, high in octane number, low in S and gum content, stable, resistant to oxidation, can make cold weather petrol due to its broad boiling point range.

10. Match the following?

   Process                              Catalyst used
i. Reforming                         A. Platinum
ii. Polymerization                   B. 65% sulfuric acid
iii. Isomerization                   C. Aluminum tri chloride

a) i-C, ii-B, iii-A
b) i-B, ii-C, iii-A
c) i-A, ii-B, iii-C
d) i-C, ii-A, iii-B

Answer: c
Clarification: The catalysts used in the processes reforming, polymerization, and Isomerization are Platinum, 65% sulfuric acid, Aluminum tri chloride over hydrochloric acid.

11. Match the following?

      Process                                   Type of reactor used
i. Catalytic cracking                          A. Tubular reactor
ii. Polymerization                             B. Cascade reactor
iii. Alkylation ( HF catalyzed)                C. Moving bed reactor

a) i-C, ii-B, iii-A
b) i-B, ii-C, iii-A
c) i-A, ii-B, iii-C
d) i-C, ii-A, iii-B

Answer: d
Clarification: The type of reactors used in the processes catalytic cracking, polymerization, and Isomerization are moving bed reactor, tubular reactor, and Cascade reactor.