Category: Engineering Chemistry Objective Questions

Engineering Chemistry Multiple Choice Questions on “Analysis of Coal”.

1. In analysis of coal, determination of _______ is done by Kjeldahl method.
a) Volatile matter
b) Nitrogen
c) Ash
d) Oxygen
Answer: b
Clarification: In ultimate analysis of coal, Nitrogen is determined by Kjeldahl method. The method involves 3 steps which are digestion, distillation and titration. In digestion, sample is digested in boiling concentrated sulphuric acid in presence of catalyst and ammonium sulphate is obtained. In distillation, excess NaOH solution is added and ammonia is obtained. In titration, ammonia is determined by volumetric acid solution. The result can be expressed in terms of %N.

2. In determination of carbon and hydrogen by ultimate analysis, increase in weight of calcium chloride bulb represents ______
a) weight of water formed
b) weight of carbon dioxide formed
c) carbon
d) hydrogen
Answer: a
Clarification: The gaseous products of combustion are passed through two bulbs. One containing weighed amount of anhydrous Calcium chloride which absorbs water other containing weighed amount of potassium hydroxide which absorbs carbon dioxide.

3. Hydrogen available for combustion is lesser than the actual one.
a) true
b) false
Answer: a
Clarification: Oxygen is present in combined form with hydrgen in the coal. It is very difficult to break hydrogen-oxygen bond and hence, that combined form of hydrogen is not available for combustion. Thus, free hydrogen available for combustion is lesser than the actual one.

4. Good quality of coal should have _____ % of oxygen.
a) low
b) high
c) 100
d) 0
Answer: a
Clarification: Good quality of coal should have less % of oxygen because increase in 1% oxygen content decreases calorific value approximately by 1.7%. Ideal fuel should have high calorific value and hence, less %oxygen.

5. Percentage of ash by analysis of coal is given by _____
a) (weight of residue/weight of sample) × 100
b) (weight of sample – weight of residue) × 100
c) (weight of sample – weight of residue)/weight of sample × 100
d) (weight of residue – weight of sample) × 100
Answer: a
Clarification: Ash is weight of residue obtained after complete combustion of 1 g of coal at 700‐750°C. Ash in % is given by, %A = (weight of residue/weight of sample) × 100.

6. In coal, Sulphur is usually present in the extent of __________
a) 0.5-3%
b) 90-95%
c) 70-75%
d) 80-85%
Answer: a
Clarification: Sulphur is generally present in the extent of 0.5 to 3% and is usually derived from ores like gypsum, iron pyrites, etc. High percentage of sulphur in coal is undesirable to be used for making coke in the iron industry since it affects the quality and properties of steel.

7. In ultimate analysis, %hydrogen is given by __________
a) (Increase in weight of CaCl₂ tube×2×100 / weight of coal sample taken×18)
b) (Increase in weight of KOH tube×2×100 / weight of coal sample taken×18)
c) (Increase in weight of CaCl₂ tube×4×100 / weight of coal sample taken×18)
d) (Increase in weight of KOH tube×4×100 / weight of coal sample taken×18)
Answer: a
Clarification: %hydrogen= (weight of hydrogen/weight of coal sample taken) × 100
In ultimate analysis of coal,
%H = (Increase in weight of CaCl₂ tube×2×100 / weight of coal sample taken×18).

8. In ultimate analysis, %carbon is given by __________
a) (Increase in weight of KOH tube×12×100 / weight of coal sample taken×44)
b) (Increase in weight of KOH tube×2×100 / weight of coal sample taken×18)
c) (Increase in weight of CaCl₂ tube×12×100 / weight of coal sample taken×44)
d) (Increase in weight of CaCl₂ tube×2×100 / weight of coal sample taken×18)
Answer: a
Clarification: %C = (weight of carbon/weight of coal sample taken) ×100
In the ultimate analysis of coal,
%C = (Increase in weight of KOH tube×12×100 / weight of coal sample taken×44).

9. __________ is the weight of residue obtained after burning a weighed amount of dry coal.
a) Ash
b) Volatile matter
c) Moisture
d) Carbon
Answer: a
Clarification: Ash is an unwanted matter and non-combustible which is the residue left after all combustible substances are burnt off. %Ash= (weight of ash formed/weight of dry coal taken) × 100.

10. In proximate analysis of coal, %fixed carbon = __________
a) 100 – % (ash + volatile matter + moisture)
b) 100 – % (ash + moisture)
c) 100 – % (ash + moisture) + %volatile matter
d) 100 – % (moisture + volatile matter)
Answer: a
Clarification: In proximate analysis of coal, firstly percentage of ash, volatile matter and moisture is found out. Percentage of fixed carbon can be found out by subtracting the above percentages from 100 since coal consists of ash, moisture, volatile matter and fixed carbon.

Engineering Chemistry Multiple Choice Questions on “Anti Knocking Agents – 2”.

1. Why is cresyl diphenyl phosphate added with petrol?
a) To increase the inductance period of the engine
b) To decrease the electrical conductivity of lead compounds
c) To increase the electrical conductivity of lead compounds
d) To decrease the inductance period of the engine
Answer: b
Clarification: Due to high traffic in cities, sometimes lead is not removed properly by ethylene dibromide. Due to this condition cresyl diphenyl phosphate is added with petrol, so that it can reduce the electrical conductivity of the lead compounds deposited on the spark plug points.

2. Which type of octane rating of petrol is used in India?
a) Ocatne-83
b) Octane-91
c) Octane-73
d) Octane- 87
Answer: d
Clarification: Before 1983 the petrol of octane rating 83 was used, while after September 1983 the petrol of octane rating 87 is used. The increase in the petrol prices is due to the shortage of crude oil.

3. How much power output can be achieved by using fuel of octane rating 100?
a) 21.3 %
b) 10.5 %
c) 26.7 %
d) 35.9 %
Answer: c
Clarification: If the compression ratio is suitably adjusted, an increase in octane number from 73 to 100 increases the power output by 26.7 % and reduces the fuel consumption by 29 %. However, there is no practical advantage of using fuel of high octane number.

4. What amount of lead is permissible for unleaded gasoline in India?
a) 13 mg/L
b) 17 mg/L
c) 21 mg/L
d) 10 mg/L
Answer: a
Clarification: With the introduction of catalytic converters, unleaded gasoline was introduced in India. If the lead concentration is less than 13 mg/L, then the gasoline is practically considered containing zero quantity of lead.

5. What happens when noble metals like platinum and palladium are used as a catalyst in catalytic converters?
a) They convert the hydrocarbon content into CO₂ and H₂O
b) They reduce NO_x emissions
c) They prone to poisoning by lead
d) They are used to decrease lead content in gasoline
Answer: c
Clarification: Catalyst made of noble metals like platinum and palladium are prone to poisoning by lead and also they are very expensive. Catalytic converter ae used to decrease the amount of lead present in gasoline. Using this type of catalyst it can reverse the reaction.

6. Which of the following does the catalytic converter consist for reduction of emissions from petrol driven vehicles?
a) Non-metal support
b) Ceramics support
c) Gels and sols support
d) Radioactive element support
Answer: b
Clarification: The catalytic converter consists of ceramic or metallic honeycomb support coated with a propriety low cost catalyst, housed in a suitably designed non-corrosive metallic housing. This catalytic converter was developed by NEERI, Nagpur.

7. Which of the following element has low toxicity than lead which can be used as anti-knocking agent, when released into environment?
a) Vanadium
b) Iron
c) Titanium
d) Manganese
Answer: d
Clarification: In environment manganese is released as Mn₃O₄ which is a less toxic gas then lead bromide. Manganese is considered as a biologically essential element. Methylcyclopentienyl manganese tricarbonyl (MMT) can be used in place of TEL as an anti-knocking agent.

8. Anti-knocking agent MMT is found to be toxic if ingested or inhaled.
a) True
b) False
Answer: a
Clarification: MMT is environmentally friendly, but it causes fouling of spark plugs and on board sensors. It causes internal problems, if ingested or is inhaled. It does reduces knocking in the engine.

9. How can we alter the hydrocarbon molecules in crude oil?
a) By fractional distillation
b) By alkylation
c) By pulverising method
d) By heating
Answer: b
Clarification: Modern petroleum refineries have the capability to alter the hydrocarbon molecules in the crude oil by cracking, alkylation and reforming processes. Knocking can be reduced by increasing the fraction of high octane compounds.

10. Which of the following aromatic compound has a greater potential to smog formation?
a) Phenol
b) Benzene
c) Toluene
d) Xylene
Answer: d
Clarification: By increasing the concentration of aromatic hydrocarbons, the knocking can be reduced to a certain level. Xylene on combustion gives rise to a lot of smoke which on mixing with fog in winter season forms smog which causes many respiratory diseases.

Engineering Chemistry Multiple Choice Questions on “Causes and Effects of Corrosion”.

1. The process of deterioration of a metal due to unwanted chemical or electrochemical interaction of the metal with its environment is called ___________
a) Electrolysis
b) Electrodialysis
c) Corrosion
d) Deposition
Answer: c
Clarification: The process of deterioration of a metal due to unwanted chemical or electrochemical interaction of the metal with its environment is called corrosion. It is a natural process, which converts a refined metal to a more stable form, such as its oxide, hydroxide, or sulfide.

2. Which of the following is an example of corrosion?
a) Rusting of iron
b) Tarnishing of silver
c) Liquefaction of ammonia
d) Rusting of iron and tarnishing of silver
Answer: d
Clarification: Rusting of iron and tarnishing of silver are examples of corrosion which is caused by the oxidation process.

3. How many rust will be formed when 100kg of iron have completely rusted away?
a) 100 kg
b) 190 kg
c) 250 kg
d) 320 kg
Answer: b
Clarification: 190 kg of rust will be formed when 100kg of iron have completely rusted away.

4. Metals does not exist in nature in the form of ___________
a) Nitrates
b) Sulphates
c) Carbonates
d) Oxides
Answer: a
Clarification: Metals exist in nature in the form of oxides, sulphides, sulphates and carbonates.

5. Which of the following is the most stable state of metal?
a) Ore of metal
b) Pure metal
c) Corroded metal
d) Metal ion
Answer: a
Clarification: Ore of metal is a thermodynamically most stable form of metal. It does not undergo any alteration in the form of ore without the use of any external force.

6. Due to corrosion, useful properties of metals such as malleability, ductility and electrical conductivity are lost.
a) True
b) False
Answer: a
Clarification: Due to corrosion, useful properties of metals such as malleability, ductility and electrical conductivity are lost. Corrosion deteriorate the metal and alloys and make them useless by altering their properties.

7. Select the incorrect statement from the following option.
a) Replacement of corroded equipment is time-consuming
b) Corrosion causes contamination of product
c) Corrosion increases the electrical conductivity of metals
d) Corrosion causes leakage of toxic liquid or gases
Answer: c
Clarification: Corrosion decreases the electrical conductivity of metals. All the other options are correct.

8. Leakage of inflammable gas from a corroded pipe can cause ___________
a) Acidity
b) Alkalinity
c) Turbidity
d) Fire hazards
Answer: d
Clarification: Leakage of inflammable gas from a corroded pipe can cause fire hazards. It will not cause acidity, alkalinity or turbidity.

Engineering Chemistry Multiple Choice Questions on “Detergents”.

1. Detergents are synthetic soaps like cleansing agents and are also known as ____________
a) Artifacts
b) Detritus
c) Syndets
d) Collagen
Answer: c
Clarification: Detergents are synthetic soaps like cleansing agents and are also known as syndets. They are a mixture of surfactants with “cleaning properties in dilute solutions.

2. Which of the following is also known as invert detergents?
a) Anionic detergents
b) Cationic detergents
c) Non-ionic detergents
d) All detergents comes in the category of invert detergents
Answer: b
Clarification: Cationic detergents are also known as invert detergents. In cationic detergent, the ammonium center is positively charged.

3. Which of the following is an example of non-ionic detergent?
a) Alkyltrimethyl ammonium chloride
b) Sodium salts of alkyl sulphates
c) Sodium salts of alkyl benzene sulphonic acids
d) Polyethers
Answer: d
Clarification: Polyethers derived from ethylene oxide is an example of non-ionic detergent.

4. Which of the following is an example of cationic detergent?
a) Alkyltrimethyl ammonium chloride
b) Sodium salts of alkyl sulphates
c) Sodium salts of alkyl benzene sulphonic acids
d) Polyethers
Answer: a
Clarification: Alkyltrimethyl ammonium chloride is an example of cationic detergent as its ammonium center is positively charged.

5. The detergents which bear negative charge at the soluble end of the chain are called anionic detergents.
a) True
b) False
Answer: a
Clarification: The detergents which bear negative charge at the soluble end of the chain are called anionic detergents. Typical anionic detergents are alkyl benzene sulfonates.

6. If the carbon chain is highly branched, the corresponding detergent will be ____________
a) Soft and biodegradable
b) Soft and non-biodegradable
c) Hard and biodegradable
d) Hard and non-biodegradable
Answer: d
Clarification: If the carbon chain is highly branched, the corresponding detergent will be hard and non-biodegradable.

7. If the carbon chain is linear, the corresponding detergent will be ____________
a) Soft and non-biodegradable
b) Soft and biodegradable
c) Hard and biodegradable
d) Hard and non-biodegradable
Answer: b
Clarification: If the carbon chain is linear, the corresponding detergent will be soft and biodegradable.

8. The % weight of detergent in washing powders is ____________
a) 5 – 10
b) 50 – 70
c) 15 – 30
d) 30 – 45
Answer: c
Clarification: The weight of detergent in washing powders is 15-30% which is quite high as compared to soaps.

9. Which of the following chemical is added in washing powder for keeping the dirt suspended in water?
a) Sodium silicate
b) Inorganic phosphate
c) Carboxy-methyl cellulose
d) Sodium perborate
Answer: c
Clarification: Carboxy-methyl cellulose is added in washing powder for keeping the dirt suspended in water while others are used for bleaching and stabilizing action.

10. Which of the following chemical is added in washing powder for keeping it dry?
a) Sodium silicate
b) Inorganic phosphate
c) Carboxy-methyl cellulose
d) Sodium perborate
Answer: a
Clarification: Sodium silicate is added in washing powder for keeping it dry while others are used for fragrance and cleansing action.

Engineering Chemistry Multiple Choice Questions on “Hybridisation”.

1. Hybridisation of Acetylene is _____________
a) sp
b) sp²
c) sp³
d) dsp²
Answer: a
Clarification: The Acetylene molecule is C₂H₂. It is sp hybridised.

2. Shape of PCl₅ molecule is _____________
a) Tigonal Planar
b) Linear
c) Trigonal bipyramidal
d) Tetrahedral
Answer: c
Clarification: PCl₅ is trigonal bipyramidal with its bond angle equal to 120⁰ and 90⁰.

3. Predict the shape of the H₂O compound based upon concepts of hybridisation.
a) Tetrahedral
b) Angular or bent structure
c) Trigonal Planar
d) Pyramidal
Answer: b
Clarification: The water molecule has angular or bent structure due to the presence of two lone pairs which repels strongly.

4. Which of the following is an example of sp₃d₂ hybridised molecule?
a) HCHO
b) ClO₄^–
c) SF₆
d) PF₅
Answer: c
Clarification: The SF₆ molecule is sp₃d₂ hybridised and the shape is regular octahedron.

5. Number of chlorine atoms which form equatorial bonds in PCl₅ molecule are ____________
a) 1
b) 2
c) 3
d) 4
Answer: c
Clarification: In PCl₅ molecule, three chlorine atoms which lie at an angle of 120⁰ in the same plane forms equatorial bonds and the other two atoms forms axial bonds at an angle of 90⁰.

6. Due to unsymmetrical structure, the molecules having sp₃d hybridisation are ____________
a) more stable and more reactive
b) less stable and more reactive
c) more stable and less reactive
d) less stable and less reactive
Answer: b
Clarification: In sp₃d hybridisation, due to its unsymmetrical structure the molecules are in the shape of trigonal bipyramidal which is less stable and more reactive.

7. The bond angles in sp₃d₂ hybridisation is ____________
a) 90⁰
b) 120⁰
c) 109.5⁰
d) 180⁰
Answer: a
Clarification: All the bond angles are equal in sp₃d₂ hybridisation i.e., 90⁰.

8. The percentage p-character in sp₃ hybridisation is ____________
a) 25%
b) 50%
c) 75%
d) 66.67%
Answer: c
Clarification: In sp₃ hybridisation, s-character is 25% and p-character is 75%.

9. All the hybridised orbital are not equal in energy and shape.
a) True
b) False
Answer: b
Clarification: All the hybridised orbital are equal in energy and shape. They are similar to each other and possess equal energy levels.

10. The hybridisation of BeF_3- is _____________
a) sp₃
b) sp
c) sp₂
d) d₂sp₃
Answer: c
Clarification: The hybridisation of BeF₃– is sp₂ and it is trigonal planar.

Engineering Chemistry Multiple Choice Questions on “Crystallisation”.

1. Which of the following is not a common method used for purification?
a) Sublimation
b) Crystallisation
c) Electrolysis
d) Chromatography
Answer: c
Clarification: Sublimation, crystallisation, distillation, differential extraction and chromatography are some of the common methods used for purification. Electrolysis process is not used for this purpose.

2. Crystallisation is based on the ____________
a) Difference in melting point
b) Difference in boiling point
c) Difference in pressure
d) Difference in solubility
Answer: d
Clarification: Crystallisation is based on the difference in the solubility of the compound and the impurities in a suitable solvent.

3. Which of the following is the example of crystallisation process?
a) Purification of alum
b) Purification of sea water
c) Separation of gases from air
d) None of the mentioned
Answer: a
Clarification: An impure sample of alum or copper sulphate is purified by crystallisation process. Purification of sea water is example of distillation process.

4. At room temperature, the impure compound in crystallisation is ____________
a) Soluble
b) Sparingly soluble
c) Insoluble
d) None of the mentioned
Answer: b
Clarification: The impure compound is sparingly soluble in a solvent at room temperature but appreciably soluble at higher temperatures.

5. Which of the following is known as mother liquor?
a) Solvent
b) Solute
c) Solution
d) Filtrate
Answer: d
Clarification: The filtrate is also known as mother liquor. A mother liquor is the part of a solution that is left over after crystallization. It is encountered in chemical processes including sugar refining.

6. The solution of impure compound and solvent is concentrated to get ____________
a) Unsaturated solution
b) Undersaturaed solution
c) Saturated solution
d) Oversaturated solution
Answer: c
Clarification: The solution of impure compound and solvent is concentrated to get a saturated solution. The solution is filtered to remove insoluble impurities.

7. Insoluble impurities from solution during crystallization are removed by ____________
a) Drying
b) Filtration
c) Heating
d) Cooling
Answer: b
Clarification: Insoluble impurities from solution during crystallization are removed by filtration. The solution is filtered to remove insoluble impurities.

8. The solution which is obtained after filtration is ____________
a) Suspended solution
b) Clear solution
c) Colloidal solution
d) None of the mentioned
Answer: b
Clarification: The solution which is obtained after filtration is a clear solution. The solution is filtered to remove insoluble impurities.

9. Crystal phases can be inter-converted by varying ____________
a) Temperature
b) Pressure
c) Size
d) Viscosity
Answer: a
Clarification: Crystal phases can be inter-converted by varying factors such as temperature.

10. The nature of the crystallization process is governed by _____________
a) Thermodynamics
b) Kinetic factors
c) Thermodynamics and Kinetic factors
d) None of the mentioned
Answer: c
Clarification: The nature of the crystallization process is governed by both thermodynamic and kinetic factors.