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Multiple choice question for engineering

Set 1

1. What happens when the apparatus is smaller?
a) Fewer side reactions
b) Equilibrium defined
c) More velocity
d) All of the mentioned

View Answer

Answer: d [Reason:] In hydrogenation we get higher pressures, where the apparatus is smaller, under such conditions, the reaction velocity is increased; the equilibrium positions are made more favourable; the reaction path is better defined, with fewer side reactions; and heating and cooling and heat interchange are facilitated.

2. The time of contact with the catalyst in autoclaves depend on?
a) Temperature
b) Reactants
c) Rate of pumping
d) All of the mentioned

View Answer

Answer: c [Reason:] In autoclaves, the time of contact with the catalyst being dependent on the rate of pumping.

3. With the use of which pump water can be pumped into the hydrogen-control tank?
a) One unit proportionating pump
b) Two-unit proportioning pump
c) Three-unit proportioning pump
d) None of the mentioned

View Answer

Answer: b [Reason:] With the use of a two-unit proportioning pump, water can be pumped into the hydrogen-control tank to bring it back to pressure and thus make up for the hydrogen consumed in the reaction.

4. Which type of reaction is hydrogenation?
a) Exothermic
b) Endothermic
c) Neutral
d) None of the mentioned

View Answer

Answer: a [Reason:] Hydrogenation reactions are usually exothermic, so that once the process is started, the problem may be one of heat removal.

5. Which of the following are vessels used as reactors for commercial operations?
a) Tape-wound
b) Forgings
c) Valves and closure
d) All of the mentioned

View Answer

Answer: d [Reason:] Different types of forgings and tape-wound vessels for use as reactors for commercial operations, along with heat exchangers, types of closures, valves, and instrumentation are described in the literature.

6. Valves are an important part of any high-pressure operation.
a) True
b) False

View Answer

Answer: a [Reason:] Valves are an important part of any high-pressure operation, and in coal hydrogenation they have to withstand hydrogen embrittlement, corrosion, creep at high temperatures, and erosion from solid-liquid mixtures at temperatures of 1000°F and pressures of 10,000 psig.

7. Which type of unit is high pressure autoclave?
a) Large
b) Small
c) Moderate
d) None of the mentioned

View Answer

Answer: b [Reason:] A high pressure autoclave is a small-scale continuous unit.

8. Autoclave does not consists of a reflux condenser.
a) True
b) False

View Answer

Answer: b [Reason:] Autoclave consists of a reflux condenser.

Set 2

1. How does para-isomers react during Sulfonation reaction?
a) Slowly
b) Rapidly
c) Does not affect
d) None of the mentioned

View Answer

Answer: a [Reason:] Isomeric compounds show pronounced differences in ease of sulfonation. The para isomer of xylene is more difficult to react; this result is in agreement with the general rule that an entering sulfonate group tends for steric reasons to avoid entering a position adjacent to other substituents, since it is fairly bulky.

2. Which of the following Sulphates fastest?
a) Tertiary
b) Secondary
c) Primary
d) None of the mentioned

View Answer

Answer: c [Reason:] Sulfation of alcohols with sulfuric acid has shown that primary alcohols sulfate ten times as fast as secondary, because tertiary provides hindrance to reactions.

3. Sulfoalkylating agents are which type of Sulfonate?
a) Inorganic
b) Organic
c) Saturated
d) None of the mentioned

View Answer

Answer: b [Reason:] Sulfoalklyating agents are called Organic sulfates because they contain one to three carbon atoms and a reactive functional group (e.g., hydroxyl, aldehyde, or olefinic un saturation) allowing easy attachment to an organic compound of higher molecular weight (e.g., a water-insoluble dye) upon which it is desired to confer the properties of a sulfonate group, especially water solubility.

4. Is use of Excessive Sulfonating agents good for industrial processes?
a) Yes
b) No
c) None of the mentioned
d) Depends on other factors

View Answer

Answer: a [Reason:] Use of excess sulfonating agent does improve the yield and is standard laboratory and industrial practice even though complete reaction is still not achieved.

5. What effect does removal of Sulphuric acid has on Chlorosulfonation reaction?
a) Complete the reaction
b) Increases the activation energy
c) Acts as an inhibitor
d) None of the mentioned

View Answer

Answer: a [Reason:] Removal of the sulfuric acid formed by chemical means has also been considered as a method for completing the chlorosulfonation reaction.

6. Substitution of the hydrocarbon ring with what increases the ease of sulfonation?
a) Hydroxy group
b) Amino group
c) Alkyl group
d) All of the mentioned

View Answer

Answer: d [Reason:] Substitution of the hydrocarbon ring with hydroxyl or amino groups, or with successive alkyl groups, increases the ease of sulfonation as reflected by the rate of reaction.

7. Isomeric compounds have no pronounced differences in ease of sulfonation.
a) True
b) False

View Answer

Answer: b [Reason:] Isomeric compounds show pronounced differences in ease of sulfonation. The para isomer of xylene is more difficult to react than the other two; this result is in agreement with the general rule that an entering sulfonate group tends for steric reasons to avoid entering a position adjacent to other substituents, since it is fairly bulky.

8. What prevents the formation of Sulfonated compounds with SO3?
a) Mercury catalyst
b) Steric hindrance
c) All of the mentioned
d) None of the mentioned

View Answer

Answer: b [Reason:] Steric hindrance prevents formation of the difficultly sulfonatable addition compound with S03.

9. Which compound state is the most difficult to Sulfonate?
a) Primary
b) Secondary
c) Tertiary
d) None of the mentioned

View Answer

Answer: c [Reason:] A study of the sulfation of alcohols with sulfuric acid has shown that primary alcohols sulphate ten times as fast as secondary. Therefore tertiary compounds are the most difficult to sulfonate.

10. Does Time of the reaction has any effect on efficiency of reaction?
a) Yes
b) No
c) None of the mentioned
d) Doesn’t depend on it

View Answer

Answer: a [Reason:] To obtain maximum efficiency in commercial sulfonation and sulfation, the reaction time must be reduced to the minimum compatible with product quality and yield.

11. Low temperatures with correspondingly long reaction periods is more useful.
a) True
b) False

View Answer

Answer: a [Reason:] Low temperatures with correspondingly long reaction periods tend to yield purer and lighter-coloured products.

12. Reaction temperature is often important in determining which ratio?
a) Mono- to polysulfonates
b) Mono- to Disulphates
c) Poly- to monosulfonates
d) All of the mentioned

View Answer

Answer: a [Reason:] Reaction temperature is often important in determining the ratio of mono- to polysulfonates.

Set 3

1. In SO3 reaction, which is/are the important variable that determines the rate and course of the reaction?
a) Solvent
b) Catalyst
c) Chemical structure
d) All of the mentioned

View Answer

Answer: d [Reason:] When employing SO2 or its compounds for sulfonation or sulfation, important variables determining the rate and course of the reaction are (1) concentration of SO3 in the sulfonating agent, (2) chemical structure of the organic compound, (3) time in relation to temperature and reagent strength, (4) catalysts, and (5) solvents.

2. Sulphuric acid and oleum are also called ______ of SO3.
a) Hydrates
b) Alcohol
c) Amines
d) Oxides

View Answer

Answer: a [Reason:] the hydrates of SO3 (i.e., sulfuric acid and oleum) are properly regarded as solutions of SO3 in water.

3. What happens to the rate of Sulfonation, if concentration of water decreases?
a) Increases
b) Decreases
c) Both of these
d) Does not depend on it

View Answer

Answer: a [Reason:] As the concentration of water increases, the rate of sulfonation steadily decreases, since the reaction rate is inversely proportional to the square of the water concentration.

4. Complete the following reaction: RH + H2SO4 ——-> _______ + H2O.
a) RSOH
b) RSO2H
c) RSO3H
d) None of the mentioned

View Answer

Answer: c [Reason:] The following reaction is known as Hydrates of SO3, and the reaction is as: RH + H2SO4 ——-> RSO3H + H2O.

5. Excess acid can be used to achieve maximum completion of reaction.
a) True
b) False

View Answer

Answer: a [Reason:] Excess acid is also used to achieve maximum completion of reaction in the sulfation of alcohols. Thus, lauryl alcohol is reacted to the extent of 90 per cent by employing a 70 per cent excess of monohydrate acid, Oleum gives excessive decomposition.

6. What is meant by ‘Baking process’?
a) Forward reaction
b) Continous heat
c) Evaporation of water
d) All of the mentioned

View Answer

Answer: c [Reason:] In the baking procedure, water is removed at high temperature by circulating air or by the use of vacuum.

7. Why do we add BF3 in Sulfonation reactions?
a) Completes the reaction
b) Forward the reaction
c) Removes water
d) All of the mentioned

View Answer

Answer: d [Reason:] Sulfonation can also be completed by adding to the sulfonation mixture a material capable of reacting with the water formed, thereby removing it and allowing this reaction to go to completion. The introduction of BFa accomplishes this.

8. What is the formula of thionyl chloride?
a) SO2Cl
b) SOCl2
c) SCl3
d) None of the mentioned

View Answer

Answer: b [Reason:] The formula of thionyl chloride is SOCl2, which also used for the removal of water in sulfonation reaction.

9. Formation of the sulfuric acid by chemical means has also been considered as a method for completing the chlorosulfonation reaction.
a) True
b) False

View Answer

Answer: b [Reason:] Removal of the sulfuric acid formed by chemical means has also been considered as a method for completing the chlorosulfonation reaction, this way the reaction moves in forward direction.

10. Which of the following compounds make Sulfonation difficult?
a) Halogen compounds
b) Nitro compounds
c) Carbonyl compounds
d) All of the mentioned

View Answer

Answer: d [Reason:] Halogen, nitro, carbonyl, and sulfonyl groups make sulfonation more difficult. It will therefore be seen that (aside from halogen which is only mildly deactivating) ortho-para directing groups facilitate ring sulfonation, while meta directing groups hinder sulfonation.

Set 4

1. Which of the following does not affect the reaction rate?
a) Solubility
b) Agitation
c) Nitro group
d) None of the mentioned

View Answer

Answer: d [Reason:] A number of factors accelerate or retard the replacement of atoms or radicals by the amino group. These will be discussed in the following order: (1) solubility, (2) agitation, (3) halogen derivative treated, (4) presence of nitro groups, and (5) temperature of amination and NH3 concentration.

2. Anthraquinonesulfonic acids are more readily converted to amines than the insoluble halogen compounds.
a) True
b) False

View Answer

Answer: a [Reason:] The soluble anthraquinonesulfonic acids are more readily converted to amines than the insoluble halogen compounds.

3. Which factor increases the partial pressure in a reaction?
a) NH3 concentration
b) Heat
c) Agitation
d) All of the mentioned

View Answer

Answer: a [Reason:] Reaction can be facilitated by increasing either the NH3 concentration or the temperature, as both the factors incidentally increase the partial pressure or activity of the dissolved ammonia.

4. When we dilute NH3 solution, does the reaction suffer?
a) Yes
b) No

View Answer

Answer: a [Reason:] When more dilute NH3 solutions are employed, the results obviously suffer from the increased activity of the solvent-water.

5. Homogeneity of reaction is highly important in which phase?
a) Vapour
b) Liquid
c) Solid
d) All of the mentioned

View Answer

Answer: b [Reason:] In liquid-phase ammonolysis, the rate of amination depends upon the homogeneity of the reaction mass.

6. Liquid phase reaction are possible without agitation.
a) True
b) False

View Answer

Answer: b [Reason:] Without agitation, some insoluble compounds would, on account of their greater density, settle to the bottom of the autoclave while the ammonia liquor remained as a distinct layer above it. Reaction would then take place only at the interface, and a complete conversion of the compound to the amino derivative would not be feasible.

7. Are emulsifying and wetting agents important amination process?
a) Yes
b) No

View Answer

Answer: a [Reason:] The efficacy of emulsifying and wetting agents are important in the amination process. Such agents appear to have important potential utility in the ammonolysis of aryl halides.

8. The replacement of Br atom is easier than Cl atom.
a) True
b) False

View Answer

Answer: a [Reason:] From the known activity of the halogens and the heats of formation of the halides, it would be expected that replacement of bromine atoms could be accomplished more readily than that of chlorine atoms.

9. The conversion of chlorobenzene to aniline requires what temperature?
a) Below 50°C
b) 100°C
c) 150°C
d) Above 200°C

View Answer

Answer: d [Reason:] The conversion of chlorobenzene to aniline requires a comparatively high temperature-200°C or above-and the presence of a catalyst.

10. By the introduction of which group makes the replacement of halogen atom faster?
a) Positive group
b) Negative group
c) Both of the mentioned
d) None of the mentioned

View Answer

Answer: b [Reason:] By the introduction negative groups such as the -NO2 or -COOH in the ortho or para position of the phenyl nucleus, the replacement of the halogen atom takes place more readily.

11. The introduction of more than one nitro group greatly decreases the activity of the halogen atom.
a) True
b) False

View Answer

Answer: b [Reason:] The introduction of more than one nitro group greatly increases the activity of the halogen atom.

12. What is meant by Ammonia factor?
a) Ammonia concentration
b) Intensity factor
c) Capacity factor
d) All of the mentioned

View Answer

Answer: c [Reason:] Ammonia ratio means Capacity factor, whereas Ammonia concentration means intensity factor.

13. Which of the following is/are the advantage for using excess NH3?
a) Rapid amination
b) Complete reaction
c) Large quantity
d) All of the mentioned

View Answer

Answer: d [Reason:] by utilizing a more concentrated NH3 solution for non-catalytic aminations may be summed up as follows: (1) amination is more rapid, (2) conversion of reacting compound to primary amine is more complete, (3) formation of secondary and tertiary amines and hydroxy compounds is inhibited, (4) lower reaction temperatures can be used, and (5) since larger batches can be treated.

14. The reaction-rate with aryl chlorides depends on what?
a) Ammonia ratio
b) Reaction temperature
c) Halogen compound
d) All of the mentioned

View Answer

Answer: d [Reason:] Reaction-rate studies with aryl chlorides showed that the effect of NH3 concentration on the rate of conversion in catalytic ammonolysis depends upon (1) the ammonia ratio, (2) the reaction temperature, and (3) the halogen compound.

Set 5

1. Suppose A->xBz and B->y, then the simplified grammar would be:
a) A->xyz
b) A->xBz|xyz
c) A->xBz|B|y
d) none of the mentioned

View Answer

Answer: a [Reason:] For the first step, substitute B in first production as it only produces terminal and remove B production as it has already been utilized. We get A->xBz|xyz and now, as B has no production, we eliminate the terms which hold the variable B, thus the answer remain A->xyz.

2. Given Grammar: S->A, A->aA, A->e, B->bA
Which among the following productions are Useless productions?
a) S->A
b) A->aA
c) A->e
d) B->bA

View Answer

Answer: d [Reason:] Some derivations are not reachable from the starting variable. As B is not reachable from the starting variable, it is a useless symbol and thus, can be eliminated.

3. Given:
S->…->xAy->…->w
if ____________, then A is useful, else useless symbol.
a) A is a non terminal
b) A is a terminal
c) w Î L
d) w Ë L

View Answer

Answer: c [Reason:] Whatever operation we perform in intermediate stages, if the string produced belongs to the language, A is termed as useful and if not, not a useful variable.

4. Given:
S->aSb
S->e
S-> A
A->aA
B->C
C->D
The ratio of number of useless variables to number of useless production is:
a) 1
b) 3/4
c) 2/3
d) 0

View Answer

Answer: a [Reason:] A, B, C, D are the useless symbols in the given grammar as they never tend to lead to a terminal. The productions S-> A, A->aA, B->C, C->D are also termed as useless production as they will never produce a string to the grammar.

5. Given grammar G:
S->aS|A|C
A->a
B->aa
C->aCb
Find the set of variables thet can produce strings only with the set of terminals.
a) {C}
b) {A,B}
c) {A,B,S}
d) None of the mentioned

View Answer

Answer: c [Reason:] First step: Make a set of variables that directly end up with a terminal Second step: Modify the set with variables that produce the elements of above generated set. The rest variables are termed as useless.

6. Given grammar:
S->aS|A
A->a
B->aa
Find the number of variables reachable from the Starting Variable?
a) 0
b) 1
c) 2
d) None of the mentioned

View Answer

Answer: b [Reason:] Use a dependency graph to find which variable is reachable and which is not. automata-theory-assessment-questions-answers-q6

7. Inorder to simplify a context free grammar, we can skip the following operation:
a) Removal of null production
b) Removal of useless symbols
c) Removal of unit productions
d) None of the mentioned

View Answer

Answer: d [Reason:] Inorder to simplify the grammar all of the process including the removal of null productions, unit productions and useless symbols is necessary.

8. Given a Grammar G:
S->aA
A->a
A->B
B->A
B->bb
Which among the following will be the simplified grammar?
a) S->aA|aB, A->a, B->bb
b) S->aA|aB, A->B, B->bb
c) S->aA|aB, A->a, B->A
d) None of the emntioned

View Answer

Answer: a [Reason:] Step 1: Substitute A->B Step 2: Remove B->B Step 3: Substitute B->A Step 4: Remove Repeated productions

9. Simplify the given grammar:
A-> a| aaA| abBc
B-> abba| b

a) A-> a| aaA| ababbAc| abbc
b) A-> a| aaA| ababbAc| abbc, B-> abba|b
c) A-> a| aaA| abbc, B->abba
d) None of the mentioned

View Answer

Answer: a [Reason:] Using the substitution rules, we can simply eradicate what is useless and thus produce the simplified result i.e. A-> a| aaA| ababbAc| abbc.

10. In context to the process of removing useless symbols, which of the following is correct?
a) We remove the Nullable variables
b) We eliminate the unit productions
c) We eliminate products which yield no terminals
d) All of the mentioned

View Answer

Answer: c [Reason:] In the process of removal of useless symbols, we want to remove productions that can never take part in any derivation.