Category: Engineering Chemistry Objective Questions

Tricky Engineering Chemistry Questions and Answers focuses on “Phases and Components – 2”.

1. If a system has 7 solid species and 2 gaseous species, what is the number of phases present in the system?
a) 8
b) 7
c) 9
d) 6
Answer: a
Clarification: We know that n gaseous components contribute to one phase and n solid components contribute to n phases. Therefore, we have 7+1 = 8 phases in the given system.

2. If a system has n number of gaseous components, then what is the number of phases?
a) 0
b) 1
c) n
d) 1
Answer: d
Clarification: We know that n gaseous components contribute to one phase and n solid components contribute to n phases. Therefore, we have only one phase in the given system.

3. Calculate the degree of freedom for the following reaction.
2KClO₃ ⟶ 2KCl + 3O₂ (Gas)
a) 1
b) 2
c) 3
d) 0
Answer: a
Clarification: We know that the number of phases and components in the above reaction is 3 and 2 respectively. Since it is a one component system, F = C-P+2 = 2-3+2 = 1.

4. What is the formula for the Degree of Freedom for a condensed phase rule?
a) F=C-P+2
b) F=C-P+1
c) F=C+P+2
d) F=C+P+1
Answer: b
Clarification: Since for a condensed phase rule, the pressure is accounted as atmospheric pressure so that we can represent the system in 3D. Hence the formula reduces for condensed phase rule.

5. Calculate the number of phases in a mixture of water and oil.
a) 1
b) 2
c) 3
d) 4
Answer: b
Clarification: Though the system is a mixture of two liquids, they are immiscible and hence they should be considered as two different phases. Hence the number of phases is 2.

6. Calculate the number of phases in a saturated solution of NaCl and water.
a) 2
b) 1
c) 3
d) 4
Answer: a
Clarification: We know that salt is soluble in water. So normally the number of phases is one. But under saturated condition, salt becomes insoluble in water and so the number of phases is 2 (as they form heterogeneous mixture).

7. Calculate the number of phases in an unsaturated solution of NaCl and water.
a) 2
b) 1
c) 3
d) 4
Answer: b
Clarification: Since the salt is completely miscible in water, it forms a homogeneous mixture and hence it has only one phase (miscible liquids form only one phase and only one component).

8. Calculate the number of phases in Mohr salt.
a) 2
b) 3
c) 1
d) 0
Answer: c
Clarification: Mohr salt is (NH₄)₂Fe(SO₄)₂•6H₂O. Since it is a single component (though it has many species), it has only one phase (a component with n species has only one compound).

9. What are the factors that affect phase rule?
a) Gravity
b) Electrical force
c) Magnetic force
d) Concentration
Answer: d
Clarification: Since phase rule is a property of a system, it only depends on factors like concentration, degree of freedom, solubility, equilibrium temperature, equilibrium pressure etc. (only stable factors are considered).

10. Calculate the number of phases in the transformation of rhombic to monoclinic sulphur.
a) 2
b) 1
c) 3
d) 4
Answer: a
Clarification: Since the system transforms from one form to another, under equilibrium, both the forms would exist together, and hence the system has 2 phases (under non-equilibrium, it has only one phase).

To practice Tricky questions and answers on all areas of Engineering Chemistry,

Engineering Chemistry Interview Questions and Answers focuses on “Thermoplastic Polymers – 2”.

1. Which of the following act as a catalyst in the preparation of PVC?
a) Lewis acid
b) Benzoyl peroxide
c) Potassium amide
d) Grignard reagent
Answer: b
Clarification: Benzoyl peroxide act as a catalyst in the preparation of PVC. The product of the polymerization process is unmodified PVC.

2. Select the incorrect statement from the following option.
a) PVC is colourless, odourless and non-inflammable
b) PVC has poor oil resistance and resistance to weathering
c) PVC is used for making bottles for consumable liquids
d) PVC has superior chemical resistance but is soluble in ethyl chloride
Answer: b
Clarification: PVC has excellent oil resistance and resistance to weathering. It is colorless, odourless and non-inflammable and is used for making bottles for consumable liquids. PVC has poor oil resistance and resistance to weathering.

3. The C-Cl dipole makes PVC a polymeric polar molecule.
a) True
b) False
Answer: a
Clarification: The C-Cl dipole makes PVC a polymeric polar molecule.PVC has excellent oil resistance and resistance to weathering. It is colorless, odourless and non-inflammable.

4. Plasticized PVC is not used for making ____________
a) Baby-pants
b) Bathroom curtaining
c) Pipes for drainage
d) Garden hose
Answer: c
Clarification: Plasticised PVC is not used for making pipes for drainage. It is used for making baby-pants, bathroom curtaining and garden hose.

5. Which of the following is also known as lucite?
a) Teflon
b) Polyvinyl acetate
c) Polystyrene
d) Perspex
Answer: d
Clarification: Perspex is also known as lucite. It is a solid transparent plastic made of polymethyl methacrylate.

6. Which of the following is used for making chewing gums?
a) Perspex
b) Polyvinyl acetate
c) Teflon
d) Polystyrene
Answer: b
Clarification: Polyvinyl acetate is used for making chewing gums. It is also used in handicrafts, envelope and wallpaper adhesives.

7. Which of the following statement is incorrect about the Teflon?
a) It has high density of the order 2.1 to 2.3 gm/cm³
b) It has excellent electrical insulation properties
c) It has high coefficient of friction
d) It is dense and chemically inert
Answer: c
Clarification: Teflon has very low coefficient of friction. All the other options are correct.

8. Which of the following is an application of Teflon?
a) Coatings of frying pans
b) Combs and brush handles
c) Audio cassettes
d) Optical fibres
Answer: a
Clarification: Coatings of frying pans, non-lubricating bearings, wire and cable insulation etc are some of the applications of Teflon. it is also used as liners in hose assembly.

9. Polystyrene is prepared by ___________ polymerisation of styrene.
a) Condensation
b) Free radical
c) Anionic
d) Cationic
Answer: b
Clarification: Polystyrene is prepared by free radical polymerisation of styrene in the presence of benzoyl peroxide as catalyst.

10. The softening temperature of polystyrene is ____________
a) 10-20 ⁰C
b) 30-50 ⁰C
c) 80-100 ⁰C
d) 120-150 ⁰C
Answer: c
Clarification: The softening temperature of polystyrene is 80-100 ⁰C. Polystyrene is a vinyl polymer. Structurally, it is a long hydrocarbon chain, with a phenyl group attached to every other carbon atom.

11. Due to the chain stiffening effect of a benzene ring, polystyrene is hard but brittle.
a) True
b) False
Answer: a
Clarification: Due to chain stiffening effect of a benzene ring, polystyrene is hard but brittle. Polystyrene is also used for producing disposable plastic cutlery and dinnerware

12. Which of the following is an application of polystyrene?
a) Insulators for motors
b) Dome-shaped covers for solar collectors
c) Laminates for printed circuitry
d) Containers for talcum powder
Answer: d
Clarification: Containers for talcum powder, combs and brush handles, audio cassettes etc are some of the applications of polystyrene. But it is not used as insulators for motors or covers for solar collectors.

areas of Engineering Chemistry for Interviews,

Engineering Chemistry Multiple Choice Questions on “Determination of Calorific Value of Solid and Non-Volatile Liquid Fuels – 1”.

1. What is the use of a bomb calorimeter?
a) To calculate the calorific value of a volatile liquid
b) To calculate the calorific value of a gas
c) To calculate the calorific value of a non-volatile liquid
d) To calculate the calorific value of sparingly soluble salt
Answer: c
Clarification: It can also be used for calculating the calorific value of solids. If the compound in a volatile liquid or gas, the flame calorimeter offers itself as an instrument due to which further processes cannot take place.

2. Why does bomb calorimeter require high pressure oxygen?
a) To increase the rate of reaction
b) To ensure that the given sample in the crucible burns completely
c) To increase the ignition temperature
d) To increase the kinetic energy
Answer: b
Clarification: A pressure of 30 bar should be used to carry out this whole process. The oxygen assists in the burning of coal sample.

3. Which material is used in the making of the cylindrical bomb?
a) Carbon steels
b) Alloy steels
c) Ferritic stainless steels
d) Austenitic stainless steels
Answer: d
Clarification: These steels are used to prevent the bomb from corrosion. These steels are also capable of withstanding a pressure of at least 50 atm.

4. What is the role of the small ring attached to the electrode in a bomb?
a) It acts as a support to the crucible
b) It is used to connect the electrode and the crucible
c) It is used as an intermediate for magnesium wire
d) It helps to collect the fuel at a point in the crucible
Answer: a
Clarification: Since the electrode connected is of tubular form, the ring attached to it makes good support between them. This electrode also acts as an oxygen inlet.

5. Why does the copper calorimeter surrounded by an air jacket and water jacket respectively in a bomb?
a) To resist the calorimeter with moisture particles
b) To carry out the process of combustion
c) To prevent the loss of heat due to radiation
d) To provide stability to the crucible inside the bomb
Answer: c
Clarification: When there is a change in temperature inside the bomb, there is a loss of heat due to radiation which is then absorbed by the air jacket and water jacket present in it.

6. Why only Beckmann or fixed zero thermometer are used to note down the temperature reading?
a) Since they can read temperature difference upto 1/100th of a degree
b) Since they have a high mercury level
c) Since they give a precise value of the temperature
d) Since they give accurate readings when dissolved in water
Answer: a
Clarification: When the current is supplied from a 6 volt battery, then there is a rise in temperature, due to which some temperature change occurs which is very small, so to calculate a perfect value for this temperature change Beckmann thermometer is used.

7. What is the use of gas releasing pin in the bomb?
a) To remove the oxygen gas from the bomb
b) To release the pressure from the bomb
c) To release the water vapour
d) To remove the carbon containing gases (such as CH₄, CO₂ etc)
Answer: b
Clarification: The pressure required in the bomb should be constant, so as to measure the change in enthalpy of the solution. Sometimes when the value of pressure is increased above to the suitability of the bomb, then to keep the pressure constant gas releasing pin is used.

8. Which material is used for making the wires, which are connected to the crucible containing fuel sample?
a) Arsenic
b) Phosphorous
c) Sulphur
d) Magnesium
Answer: d
Clarification: Since these wires are connected to the electrode from the crucible, they should be good conductors. Platinum is also used for this process.

9. What is the basic formulae for calculating gross calorific value in bomb calorimeter?
a) θ = [(W+w)(t₂+t₁)]/m
b) θ = [(W-w)(t₂-t₁)]/m
c) θ = [(W+w)(t₂-t₁)]/m
d) θ = [(W+w)(t₂+t₁)]/m
Answer: c
Clarification: Its unit is cal/gm. Here t₂-t₁ is the temperature difference and W+w is the total weight.
θ = [(W+w)(t₂-t₁)]/m
where θ is gross calorific value, W is the weight of the water sample taken in calorimeter, w is the weight of water equivalent, t₁ is the initial temperature, t₂ is the final temperature and m is the weight of the fuel sample taken respectively.

Engineering Chemistry Multiple Choice Questions on “Petroleum – 2”.

1. Which of the following area contains crudes of mixed base oils?
a) Ankaleswar
b) Cambay
c) Naharkatiya
d) Mumbai
Answer: c
Clarification: The Naharkatiya oil fields in Assam contain crudes of mixed base oils. The Ankaleswar and Cambay oil field present in Gujrat mainly consists of paraffin base type. Extensive exploration of oil in all prospective sedimentary basins of India is in progress.

2. How much percentile of petroleum is present in India?
a) 20%
b) 10%
c) 5%
d) 1%
Answer: d
Clarification: The Indian resources of petroleum are estimated to be around 300 million tonnes. The total world reserves of petroleum are around 30000 tonnes which are mainly present in the gulf regions.

3. Which of the following deltas of petroleum are found recently in India?
a) Godavari
b) Naharkatiya
c) Cambay
d) Gulf of Kutch
Answer: a
Clarification: Oil deposits are obtained from the exploration of the Godavari delta. The production of petroleum high is still in progress. Also in the Gulf of Kutch there is still exploration going on.

4. In which region of Uttar Pradesh oil refinery is located?
a) Lucknow
b) Mathura
c) Agra
d) Lalganj
Answer: b
Clarification: Mathura oil refinery is the sixth refinery founded by the India Oil Corporation Limited. This refinery was founded for meeting the demands of petroleum products in the north-western region of the country.

5. Which of the following method is used for the detection of deposits of oil by mapping the age of rock?
a) Visual method
b) Seismic method
c) Drilling
d) Geological method
Answer: d
Clarification: As the name suggests, this method comprises of mapping the age of rocks, their nature and the types of formation present. These are sometimes assisted by aerial photography.

6. Which of the following is a geophysical method for the detection of oil deposits?
a) Gravimetric method
b) Geological method
c) Visual method
d) Drilling
Answer: a
Clarification: Gravimetric method is the method in which the variations in density of the earth’s crust are measured with sensitive instruments. There are more two types of geophysical method which includes a seismic method and magnetic method.

7. For what purpose does the cores for drill are examined?
a) For the fossil fuels occurring in strata
b) For mapping the age of rocks
c) For fossil formation and evidence of non-porous rocks
d) For checking the intensities of earth’s magnetic field
Answer: c
Clarification: Drilling provides the final proof for the occurrence of oil-bearing strata. When the existence of oil deposit is proved, drilling is continued until the depth of the oil or oil-bearing strata is confirmed.

8. What is the tall huge tower present the drilling called?
a) Feed lever
b) Derrick
c) Chuck and sleeve
d) Slurry
Answer: b
Clarification: The drilling equipment consists of a tall huge tower called derrick, which is anchored to the ground, engines, mud pumps, water tanks draw-works nad many other modules.

9. The success of drilling mostly depends on the quality of the specially prepared slurry of water called the mud.
a) True
b) False
Answer: a
Clarification: This mud formed is generally oil based or water based. The mud consists of various chemicals, adhesives and special additives that serve important functions.

10. Which of the following is used as a special additive in water-based drilling fluids?
a) NaOH
b) KCl
c) Baryte
d) NaCl
Answer: d
Clarification: NaCl is the additive that is used to minimize borehole washouts in a salt zone. NaOH, KCl and Baryte are the chemicals used in water based mud. NaOH is used for pH control.

11. Which of the following condition must be satisfied for the mining of petroleum?
a) A non-porous rock
b) A cap rock overlying the reservoir rock
c) A fully opened area
d) Proper temperature and pressure conditions
Answer: b
Clarification: The cap rock is impermeable to the oil and hence prevents the escape of oil upwards through the strata above. A porous rock is required. A closure is also required to restrict or prevent lateral migration.

12. How can we dig out the oil present in the earth’s crust?
a) By providing some external pressure
b) By digging the whole area
c) The oil comes out by itself from pipes
d) By covering the holes at the top
Answer: c
Clarification: Holes are drilled into the earth’s crust and pipes are sunk up to the surface of oil-bearing rocks. Oil usually rushes out to the surface by itself because of hydrostatic pressure of natural gas.

13. Which type of pumps are used for pumping the oil?
a) Air-lift pump
b) Piston pump
c) Screw pump
d) Gear pump
Answer: a
Clarification: When the hydraulic pressure of the gas becomes too low, it may have to be mechanically pumped up with the help of air-lift pump. It consist of two coaxial pipe which are sunk into the oil bed.

14. When the mixture of gas and oil is forced out due pressure of gas, then this method of pumping is called water drive.
a) True
b) False
Answer: b
Clarification: This process of pumping is called pressure drive. When the oil is forced out by pumping of water into the well, when a mixture of oil and water comes out of well, then this method is called water drive.

15. Which type of process is used for the refining of petroleum?
a) Destructive distillation
b) Zone distillation
c) Fractional distillation
d) Steam distillation
Answer: c
Clarification: The crude obtained by the process of mining consist of many impurities of solid, liquid and gaseous hydrocarbons. By the process of fractional distillation the crude oil is separated on the basis of the impurity percentile.

Engineering Chemistry Multiple Choice Questions on “Alkalinity of Water and its Estimation”.

1. Which source of water is free from hardness and surface impurities?
a) Surface water
b) Underground water
c) Rain water
d) Sea water
Answer: c
Clarification: Rain water is free from hardness and surface impurities. Surface water and sea water is very impure and saline.

2. Water from reservoirs comes under the category of ____________
a) Surface water
b) Rain water
c) Underground water
d) Sea water
Answer: a
Clarification: Water from reservoirs comes under the category of surface water. Reservoirs are the large storage tanks which are used for storing and distributing water to the channels.

3. Which of the following indicator is pink in basic medium?
a) Methyl orange
b) Phenolphthalein
c) Starch
d) Litmus paper
Answer: b
Clarification: Phenolphthalein indicator is pink in basic medium, methyl orange is orange, starch is colorless and litmus paper shows different colors in different mediums.

4. The temporary hardness in water is due to ____________
a) OH^–
b) CO₃^2-
c) H⁺
d) HCO₃^–
Answer: d
Clarification: The temporary hardness in water is due to HCO₃^–. It can easily be removed by mere action of boiling.

5. With respect to the constituents causing alkalinity in water, which of the following situation never arises?
a) CO₃^2- and HCO₃^– together
b) HCO₃^– and OH^– together
c) OH^– only
d) OH^– and CO₃^2- together
Answer: b
Clarification: HCO₃^– and OH^– together combines to form CO₃^2- ions. Therefore, this situation never arises.

6. What is the disadvantage of using high alkaline water?
a) It may lead to infections
b) It may lead to electrolysis
c) It may lead to caustic embrittlement
d) It may lead to indigestion
Answer: c
Clarification: High alkaline water leads to caustic embrittlement and deposition of precipitates and sludges in boiler tubes and pipes.

7. The alkalinity due to hydroxide ion when P > M/2 will be ____________
a) M-2P
b) 2(M-P)
c) Nil
d) 2P-M
Answer: d
Clarification: The alkalinity due to hydroxide ion when P > M/2 will be (2P-M).

8. The alkalinity due to bicarbonate ion when P < M/2 will be ____________
a) M-2P
b) 2(M-P)
c) Nil
d) 2P-M
Answer: a
Clarification: The alkalinity due to bicarbonate ion when P < M/2 will be (M-2P).

9. The alkalinity due to carbonate ion is 2P when?
a) P = M
b) P > M/2
c) P = M/2
d) P < M/2
Answer: c
Clarification: The alkalinity due to carbonate ion is 2P when P = M/2.

10. Alkalinity is a measure of the ability of water to neutralize the acids.
a) True
b) False
Answer: a
Clarification: Alkalinity is a measure of the ability of water to neutralize the acids. Measuring alkalinity is important in determining a stream’s ability to neutralize acidic pollution from rainfall or waste water.

Engineering Chemistry Multiple Choice Questions on “Electroplating Equipment and Operating Conditions”.

1. Identify the correct conditions for electroplating to take place (in K and in ATM).
a) T=200 and P=20
b) T=300 and P=25
c) T=100 and P=60
d) T=110 and P=30
Answer: b
Clarification: For electroplating to take place, the temperature must be above 0 degree Celsius (that is above 273 kelvin) and the pressure must be atmospheric pressure. Thus the suitable temperature from the above options are T=300 and P=25.

2. Which of the following is wrong about the working conditions of electroplating?
a) Temperature follows a steady state
b) Pressure follows a steady state
c) Pressure is compressed
d) Pressure is neglected
Answer: a
Clarification: If a graph between temperature and pressure is drawn, then it is seen that temperature gives a straight line (that is pressure and temperature are directly proportional). Thus temperature is maintained at steady state.

3. If the temperature of cadmium bath is maintained at 400 K and the concentration of cadmium is 70 g, calculate the pressure at that temperature (given, the gas constant is 8.314 J /mol. • K).
a) 49.2
b) 47.50
c) 39.40
d) 0
Answer: b
Clarification: According to Falton’s formula P=TR/C, where T is the temperature, R is the gas constant, C is the concentration. So, here P = 400 x 8.314/70 = 47.50.

4. If the pressure of mercury bath is maintained at 30 ATM and the concentration of mercury is 89 g, calculate the temperature at that pressure (given, the gas constant is 8.314 J/mol. • K).
a) 660
b) 456.8
c) 321.14
d) 765.09
Answer: c
Clarification: According to Falton’s formula P=TR/C, where T is the temperature, R is the gas constant, C is the concentration. Therefore T=PC/R. So, here T=30 x 89/8.314 = 312.4.

5. What will happen if the electroplating conditions are exceeded in a system?
a) The process will come to halt
b) Excess metal deposition will take place
c) Electrolyte leakage will take place
d) Impurities will not be removed
Answer: a
Clarification: When electroplating has to continue in a steady state, the conditions of temperature and pressure has to be satisfied. If the conditions exceed the normal conditions then the process comes to halt.

6. What should be the minimum amount of current that has to be passed to get leakage free metal.
a) 240 A
b) 200 A
c) 350 A
d) 100 A
Answer: d
Clarification: Though the amount of current depends on the metal that is used, the minimum amount of current required for all metals that are discovered is 100 A.

7. Where does pure metal gets deposited after passing current?
a) Cathode
b) Anode
c) Electrolyte
d) Negative pole
Answer: a
Clarification: During electroplating, impure metal is kept as anode and electrolyte is the metal salt solution. After the current has passed, the electrons will pass through the electrolyte and hence we will get the pure metal at anode.

8. What is the cause of the formation of the depletion layer?
a) Deletion in charge carriers
b) Leakage current
c) Deposition of extra layer on pure metal
d) Extra depletion
Answer: c
Clarification: When electroplating takes place, there is a value called the critical concentration where the amount of deposition is controlled by the passage of current. When this concentration exceeds, we get a depletion layer.

9. Calculate the concentration of the metal formed from the given data.
T=340
P=120
R=8.314
a) 120
b) 240
c) 23.56
d) 44
Answer: c
Clarification: According to Falton’s formula P=TR/C, where T is the temperature, R is the gas constant, C is the concentration. Therefore C = TR/P. So, here T = 340 x 8.314/ 120 = 23.56.

10. Using which formula is concentration calculated?
a) Falton method
b) Thomson method
c) Robert method
d) Lewis method
Answer: a
Clarification: Electroplating method was started in 1880 by Falton. He was the first to give the law for calculating the amount of concentration during electroplating. According to his law P=TR/C.