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Multiple choice question for engineering

Set 1

1. What is the molecular formula of lime?
a) CaCO3
b) Al(OH)3
c) Ca(OH)2
d) Mg(OH)2

View Answer

Answer: c [Reason:] The molecular formula of lime is Ca(OH) 2. It is a white caustic alkaline substance consisting of calcium oxide, which is obtained by heating limestone and which combines with water with the production of much heat.

2. What is the molecular formula of soda?
a) Na2CO3
b) Al2(SO4)3
c) Mg(OH) 2
d) Ca(OH) 2

View Answer

Answer: a [Reason:] The molecular formula of soda is Na2CO3. It is also called washing soda or soda ash.

3. Which of the following is not a precipitate in lime-soda process?
a) CaCO3
b) Fe(OH) 3
c) Al(OH) 3
d) Al2(SO4)3

View Answer

Answer: d [Reason:] Al2(SO4)3 is not a precipitate in lime-soda process. All the other options are the precipitate in lime-soda process.

4. Which of the following is not used as a coagulant in lime-soda process?
a) Alum
b) Calcium bicarbonate
c) Aluminium sulphate
d) Sodium aluminate

View Answer

Answer: b [Reason:] Calcium bicarbonate is not used as a coagulant in lime-soda process. Alum, aluminium sulphate and sodium aluminate are used as coagulants in lime-soda process.

5. What is the function of coagulant?
a) It helps in formation of fine precipitate
b) It helps in formation of coarse precipitate
c) It helps in increasing the solubility
d) It helps in increasing the boiling point

View Answer

Answer: b [Reason:] Coagulants helps in formation of coarse precipitate. C?oagulation is a process of addition of coagulant to destabilize a stabilized charged particle.

6. For the softening of one mole of magnesium bicarbonate, the number of mole of lime required is
a) 2
b) 3
c) 4
d) 5

View Answer

Answer: a [Reason:] For the softening of one mole of magnesium bicarbonate, the number of mole of lime required is two. The ratio of bicarbonate to lime in lime-soda process is 1:2.

7. The residual hardness in lime-soda process is
a) 0-2 ppm
b) 5-15 ppm
c) 15-50 ppm
d) 50-70 ppm

View Answer

Answer: c [Reason:] The residual hardness in lime-soda process is 15-50 ppm. Lime soda softening cannot produce a water at completely free of hardness because of the low solubility of CaCO3 and Mg(OH)2.

8. In lime soda process, capital cost is ___________ whereas operational expenses are __________
a) High, low
b) High, high
c) Low, low
d) Low, high

View Answer

Answer: d [Reason:] In lime soda process, capital cost is low whereas operational expenses are high. It is because the chemicals and reagents used are costly.

9. State true or false. In lime-soda process, no exchange of ions occurs.
a) True
b) False

View Answer

Answer: a [Reason:] In lime-soda process, no exchange of ions occurs. Recarbonation is used to stabilize the water. The excess lime and magnesium hydroxide are stabilized by adding carbon dioxide, which also reduces pH from 10.8 to 9.5.

10. Which of the following is the second step for calculating the amount of lime and soda?
a) Identification of lime and soda for different salts
b) Calculation of CaCO3 equivalents
c) Calculation of lime requirements
d) Calculation of soda requirements

View Answer

Answer: b [Reason:] Calculation of CaCO3 equivalents is the second step for calculating the amount of lime and soda. First step is to identify the lime and soda for different salts. and the last two steps are calculation of lime and soda requirements.

Set 2

1. Lubrication is necessary to protect wear and tear caused due to
a) Electrostatic force
b) Gravitational force
c) Frictional force
d) Magnetic force

View Answer

Answer: c [Reason:] Lubrication is necessary to protect wear and tear caused due to frictional force. Electrostatic, gravitational and magnetic forces do not cause wear and tear.

2. State true or false. Lubricant act as a coolant to carry away heat.
a) True
b) False

View Answer

Answer: a [Reason:] Lubricant act as a coolant to carry away heat and is generally used in refrigerators and air conditioners.

3. Select the incorrect statement from the following option.
a) Lubricant keep out dirt
b) Lubricant act as a seal
c) Lubricant transmit fluid power
d) Lubricant enhance corrosion

View Answer

Answer: d [Reason:] Lubricants prevents corrosion. It does not act as a seal or remove dirt and also not transmit fluid power.

4. The viscosity of petroleum oil for hydraulic lifts is
a) High
b) Low
c) Moderate
d) Very high

View Answer

Answer: b [Reason:] The viscosity of petroleum oil for hydraulic lifts is low as it makes it less dense and easier to lift up while carrying the operation.

5. The science of friction, lubrication and wear is called
a) Endiology
b) Geology
c) Tribology
d) Morphology

View Answer

Answer: c [Reason:] The science of friction, lubrication and wear is called tribology. Morphology and Geology relates to the science of Earth’s crust and rock structure.

6. On increasing the lubrication, the efficiency of the machine
a) Increases
b) Decreases
c) Remain same
d) Does not get affected

View Answer

Answer: a [Reason:] On increasing the lubrication, the efficiency of the machine increases as it increases the speed of the operations and causes less wear and tear.

Set 3

1. The purity of compound is confirmed by
a) Its melting point and boiling point
b) Chromatographic technique
c) Spectroscopy
d) All of the mentioned

View Answer

Answer: d Eplanation: The purity of compound is confirmed by its melting point and boiling point, chromatographic technique and spectroscopy.

2. Select the correct statement from the following options.
a) The transformation of solid to liquid is called melting and the reverse process is called freezing
b) The transformation of solid to liquid is called freezing and the reverse process is called melting
c) The transformation of liquid to solid is called melting and the reverse process is called freezing
d) None of the mentioned

View Answer

Answer: a [Reason:] The transformation of solid to liquid is called melting and the reverse process is called freezing.

3. The temperature at which solid and liquid coexist in equilibrium is called
a) Melting point of liquid
b) Freezing point of liquid
c) Freezing point of solid
d) All of the mentioned

View Answer

Answer: b [Reason:] The temperature at which solid and liquid coexist in equilibrium is called melting point of solid or freezing point of liquid.

4. Select the incorrect statement from the following option.
a) Every pure solid crystalline substance has a characteristic and unique melting point
b) Impure sample of substance has different melting point
c) Two different pure substances have same melting points
d) Melting point serves as the criteria of purity of a solid substance

View Answer

Answer: c [Reason:] Two different pure substances have different melting points. All the other options are correct. Every pure solid crystalline substance has a characteristic and unique melting point and impure sample of substance has different melting point. Melting point serves as the criteria of purity of a solid substance.

5. When the solid and liquid phase are in equilibrium, the temperature
a) Increases gradually
b) Decreases gradually
c) Remains constant
d) None of the mentioned

View Answer

Answer: c [Reason:] When the solid and liquid phase are in equilibrium, the temperature remains constant. The heat is absorbed in changing from one state to another, so no temperature change occurs.

6. The melting point of ice is
a) 00C
b) 1000C
c) 40C
d) -40C

View Answer

Answer: a [Reason:] The melting point of ice at 1 atmosphere of pressure is very close to 0 °C (32 °F, 273.15 K); this is also known as the ice point. In the presence of nucleating substances the freezing point of water is the same as the melting point, but in the absence of nucleators water can supercool to −42 °C (−43.6 °F, 231 K) before freezing.

7. Molar heat of fusion is defined as
a) Energy required to melt one gram of solid
b) Energy required to melt one mole of solid
c) Energy required to melt one kilogram of solid
d) Energy required to melt ten moles of solid

View Answer

Answer: b [Reason:] Molar heat of fusion is defined as energy required to melt one mole of solid at a given temperature. The molar heat of fusion refers to the enthalpy change per amount of substance in moles.

8. The temperature remains constant during phase change because the increased kinetic energy is used to overcome the cohesive forces in the liquid.
a) True
b) False

View Answer

Answer: a [Reason:] The temperature remains constant during phase change because the increased kinetic energy is used to overcome the cohesive forces in the liquid. The heat is absorbed in changing from one state to another, so no temperature change occurs.

9. The molar heat of fusion (kJ/mol) of water is
a) 1.3
b) 0.84
c) 7.61
d) 6.01

View Answer

Answer: d [Reason:] The molar heat of fusion of water is 6.01 kJ/mol. The molar heat of fusion refers to the enthalpy change per amount of substance in moles.

10. The melting point of mercury is
a) 3570C
b) -390C
c) 00C
d) 1000C

View Answer

Answer: b [Reason:] The melting point and freezing point of mercury is 234.32 kelvins (−38.83 °C or −37.89 °F).

Set 4

1. What is the molecular formula of stearate ion?
a) C17H35COO
b) C35H17COO+
c) C35H17COO
d) C17H35COO+

View Answer

Answer: a [Reason:] Sodium stearate ionises to form stearate anion(C17H35COO) and sodium cation(Na+).

2. Which part of the stearate ion is hydrophilic in nature?
a) Tail
b) Hydrocarbon chain
c) Head
d) None of the mentioned

View Answer

Answer: c [Reason:] The end of the hydrocarbon chain is having a polar group (head) which is hydrophilic in nature and represented by a hollow circle.

3. Which of the following is water insoluble?
a) COO
b) Na+
c) C17H35
d) All of the mentioned

View Answer

Answer: b [Reason:] C17H35 is hydrophobic in nature and hence it is water insoluble.

4. The number of stearate ions required to form a micelle of colloidal size is
a) 50
b) 60
c) 70
d) 80

View Answer

Answer: c [Reason:] About 70 stearate ions aggregate to form a micelle of colloidal size.

5. Select the incorrect statement from the following options.
a) In the micelle formation, the water soluble heads are directed towards the centre
b) In the micelle formation, the water soluble heads are on the surface in contact with the water
c) In the micelle formation, the water insoluble tails are directed towards the centre
d) None of the mentioned

View Answer

Answer: a [Reason:] In the micelle formation, the water insoluble tails are directed towards the centre, and the water soluble heads are on the surface in contact with water. All the other options are correct.

6. Select the correct statement from the following options.
a) The soap micelle is unstable due to positive charge on its head
b) The soap micelle is stable due to positive charge on its head
c) The soap micelle is unstable due to negative charge on its head
d) The soap micelle is stable due to negative charge on its head

View Answer

Answer: d [Reason:] The soap micelle is stable due to negative charge on its polar head. In the micelle formation, the water insoluble tails are directed towards the centre, and the water soluble heads are on the surface in contact with water.

7. The transition of ions to micelle is
a) Reversible
b) Irreversible
c) None of the mentioned
d) All of the mentioned

View Answer

Answer: a [Reason:] The transition of ions to micelle is a reversible process. In the micelle formation, the water insoluble tails are directed towards the centre, and the water soluble heads are on the surface in contact with water.

8. What is Critical Micelle Concentration?
a) The maximum amount of concentration that is required for the formation of micelle
b) The minimum amount of concentration that is required for the formation of micelle
c) The maximum amount of concentration that is not required for the formation of micelle
d) The minimum amount of concentration that is not required for the formation of micelle

View Answer

Answer: b [Reason:] The minimum amount of concentration that is required for the formation of micelle is termed as Critical Micelle Concentration (CMC). It is defined as the concentration of surfactants above which micelles form and all additional surfactants added to the system go to micelles.

9. Micelles behave as colloids only when
a) Concentration is less than CMC
b) Concentration is equal to CMC
c) Concentration is greater than CMC
d) They always behave as colloids

View Answer

Answer: c [Reason:] Micelles behave as colloids only when its concentration is greater than CMC. The CMC is an important characteristic of a surfactant. Before reaching the CMC, the surface tension changes strongly with the concentration of the surfactant. After reaching the CMC, the surface tension remains relatively constant or changes with a lower slope.

10. The conductivity of micelles is
a) Higher than colloidal solution
b) Lower than colloidal solution
c) Equals to colloidal solution
d) None of the mentioned

View Answer

Answer: a [Reason:] The conductivity of micelles is higher than the colloidal solution. And hence they can conduct more electric charges through them.

Set 5

1. The main cause of molecular aggregation is
a) Conduction
b) Induction
c) Inter-molecular interactions
d) Resonance

View Answer

Answer: c [Reason:] The main cause of molecular aggregation is inter-molecular interactions. Inter-molecular interactions stem from the electric properties of atoms. Being the cause of molecular aggregation, inter-molecular forces are at the roots of chemistry and are the fabric of the world.

2. From where does the inter-molecular interaction originate?
a) From the electric properties of atoms
b) From the cohesive properties of atoms
c) From the magnetic properties of atoms
d) None of the mentioned

View Answer

Answer: a [Reason:] Inter-molecular interactions originate from the electric properties of atoms. Inter-molecular interactions stem from the electric properties of atoms. Being the cause of molecular aggregation, inter-molecular forces are at the roots of chemistry and are the fabric of the world.

3. Which of the following is not a state of aggregation of matter?
a) Solid
b) Liquid and Gas
c) Plasma
d) None of the mentioned

View Answer

Answer: d [Reason:] Solid, liquid, gas and plasma are the four states of aggregation of matter.

4. The process by which individual molecules form the defined aggregate is called
a) Self-aggregation
b) Self-assembly
c) Aggregation
d) Assembly

View Answer

Answer: b [Reason:] The process by which individual molecules form the defined aggregate is called self-assembly. Molecular self-assembly is the process by which molecules adopt a defined arrangement without guidance or management from an outside source.

5. In water, non-polar molecules tend to aggregate because they are forced to come into close proximity with each other due to
a) Hydrophobic interactions
b) Hydrophilic interactions
c) Vander Waals interactions
d) Electrovalent interactions

View Answer

Answer: a [Reason:] In water, non-polar molecules tend to aggregate because they are forced to come into close proximity with each other due to hydrophobic interactions.

6. Which type of molecules form aggregate through a self-assembly process that is driven by the hydrophobic effect?
a) Electrophilic
b) Nucleophilic
c) Ambiphilic
d) None of the mentioned

View Answer

Answer: c [Reason:] Ambiphilic molecules form aggregate through a self-assembly process that is driven by the hydrophobic effect. Molecular self-assembly is the process by which molecules adopt a defined arrangement without guidance or management from an outside source.

7. Why metallic bonds are non-directional?
a) Because there is uniform distribution of mobile valence electrons around the kernels
b) Because there is non-uniform distribution of mobile valence electrons around the kernels
c) There is no change in inter-kernel distance
d) There is change in inter-kernel distance

View Answer

Answer: a [Reason:] Metallic bonds are non-directional because there is uniform distribution of mobile valence electrons around the kernels, provided there is no change in inter-kernel distance.

8. The number of molecules in conduction band
a) Increases with fall in temperature
b) Decreases with rise in temperature
c) Increases with rise in temperature
d) Does not depend upon the temperature

View Answer

Answer: c [Reason:] The number of molecules in conduction band increases with the rise in temperature. At high temperatures, randomness increases and more molecules move towards the conduction band.