McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Uncategorized topics .
| 51. |
Electrodialysis is based on the fact that the ions present in saline water migrate towards their respective electrodes under the influence of applied |
| A. | current |
| B. | resistance |
| C. | conductance |
| D. | emf |
| Answer» D. emf | |
| Explanation: electrodialysis is based on the fact that the ions present in saline water migrate towards their respective electrodes under the influence of applied emf. the potential difference generated between the elctrodes is the main cause of flow of electrons. | |
| 52. |
The cation selective membrane is embedded with functional groups of |
| A. | positive charge |
| B. | negative charge |
| C. | both positive as well as negative charge |
| D. | neutral |
| Answer» B. negative charge | |
| Explanation: the cation selective membrane is embedded with functional groups of negative charge as it attracts only positive charges towards them. | |
| 53. |
Electrodialysis is an electrically driven separation conducted at a very low pressure- driven, size-exclusion filtering process. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: electrodialysis is an electrically driven separation conducted at a very low pressure-driven, size-exclusion filtering process. electrodialysis is used to transport salt ions from one solution through ion- exchange membranes to another solution under the influence of an applied electric potential difference. | |
| 54. |
The ion-exchange membrane are electrically conductive and are not permeable to flow, even under pressure. |
| A. | electron |
| B. | oil |
| C. | fluorine |
| D. | water |
| Answer» D. water | |
| Explanation: the ion-exchange membrane are electrically conductive and impermeable to water flow, even under pressure. electrons can easily flow through these membranes. | |
| 55. |
Select the incorrect statement from the following option. |
| A. | electrodialysis reversal (edr) was introduced in the commercial sector to improve electrodialysis process |
| B. | the edr process and conventional ed unit operates on the same principle, except at intervals of several times an hour |
| C. | the reversal feature is useful in breaking up films, scales and other deposits |
| D. | electrodialysis process is not economical as per capital cost |
| Answer» D. electrodialysis process is not economical as per capital cost | |
| Explanation: electrodialysis process is economical as per capital cost and operational expenses are concerned. all the other options are correct. | |
| 56. |
Which one of the following is not a cation exchanger? |
| A. | amberlite |
| B. | triolite |
| C. | dowex |
| D. | duolite |
| Answer» B. triolite | |
| Explanation: triolite is not a cation exchanger. amberlite, dowex and duolite are some of the examples of the cation exchanger. | |
| 57. |
The the salt rejection, the better the system is performing. |
| A. | higher |
| B. | lower |
| C. | moderate |
| D. | poor |
| Answer» A. higher | |
| Explanation: the higher the salt rejection, the better the system is performing. a low salt rejection can mean that the membranes require cleaning or replacement. | |
| 58. |
What is the osmotic pressure for sea water? |
| A. | 1.5 mpa |
| B. | 1.8 mpa |
| C. | 2.3 mpa |
| D. | 2.45 mpa |
| Answer» D. 2.45 mpa | |
| Explanation: the osmotic pressure of sea water is 2.45 mpa. the concentration of salt in sea water is 32000-35000 mg/l. the applied pressure on the ro equipment is 5.6- 6. | |
| 59. |
Membrane permeation rate increases proportionally to effective pressure. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: although membrane permeation rate increases proportionally to effective pressure, the highest recommended applied pressure of commercial membranes presently available is 7.0 mpa. | |
| 60. |
RO membranes are made of |
| A. | plastic |
| B. | cotton |
| C. | silk |
| D. | polymer |
| Answer» D. polymer | |
| Explanation: the highest recommended applied pressure of commercial membranes presently available is 7.0 mpa; beyond which compaction will start to occur due to the fact that ro membranes are made of polymers. | |
| 61. |
Concentrated seawater which is called |
| A. | permeate |
| B. | brine |
| C. | ro water |
| D. | salt water |
| Answer» B. brine | |
| Explanation: when fresh water is separated from seawater, concentrated seawater which is called brine and is retained on the surface of the ro membrane. | |
| 62. |
7 REVERSE OSMOSIS. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: the salt concentration and the osmotic pressure of the brine are related proportionally, i.e., the osmotic pressure of the brine increases as the salt concentration increases. | |
| 63. |
The upper limit of brine concentration is |
| A. | 1.5 |
| B. | 2 |
| C. | 2.5 |
| D. | 3 |
| Answer» C. 2.5 | |
| Explanation: the upper limit of the brine concentration is usually fixed. the upper limit is normally 1.6-2.5 times that of the normal seawater. | |
| 64. |
What is the maximum acceptable limit of temperature for RO? |
| A. | 20˚c |
| B. | 30˚c |
| C. | 40˚c |
| D. | 50˚c |
| Answer» C. 40˚c | |
| Explanation: in order to reduce the effects of temperature to a minimum, the acceptable | |
| 65. |
What is the design temperature of RO systems? |
| A. | 20˚c |
| B. | 25˚c |
| C. | 30˚c |
| D. | 35˚c |
| Answer» B. 25˚c | |
| Explanation: ro systems are usually designed to operate at 25°c and water flux falls by 20–25 percent when water temperature is lowered by 10°c. | |
| 66. |
What is the thumb rule to consider for osmotic pressure? |
| A. | 1 psi for every 86 ppm of na |
| B. | 2 psi for every 86ppm of na |
| C. | 1 psi for every 43 ppm of na |
| D. | 2 psi for every 43 ppm of na |
| Answer» A. 1 psi for every 86 ppm of na | |
| Explanation: the tendency of a pure solution constituting low solute concentration to flow into solution constituting higher solute concentration is known as osmosis. when pressure greater than osmotic pressure is applied then reverse osmosis takes place. the thumb rule for the consideration of osmotic pressure is 1 psi for every 86 ppm of na. | |
| 67. |
What is the flux considered while designing a reverse osmosis system for treating RO permeate? |
| A. | 30-40 lmh |
| B. | 12-18 lmh |
| C. | 20-25 lmh |
| D. | 25-30 lmh |
| Answer» A. 30-40 lmh | |
| Explanation: flux is the amount of water flowing through a particular area. this is dependent both on the nature of water and the membrane surface area. the flux considered for ro permeate is 30-40 lmh. | |
| 68. |
What is the flux considered while designing a reverse osmosis system for treating bore well water? |
| A. | 30-40 lmh |
| B. | 40-50 lmh |
| C. | 20-30 lmh |
| D. | 12-18 lmh |
| Answer» C. 20-30 lmh | |
| Explanation: the flux increases with increase in pressure. it also increases with increase in temperature. in case of bore well water, the flux considered is 20-30 lmh. | |
| 69. |
What is the flux considered while designing a reverse osmosis system for treating surface water? |
| A. | 15-22 lmh |
| B. | 22-30 lmh |
| C. | 12-15 lmh |
| D. | 30-35 lmh |
| Answer» A. 15-22 lmh | |
| Explanation: the flux to be considered depends on the nature of the water to be treated. the flux is used to determine the number of membranes required for the treatment system. in the case of treating surface water by a conventional method the flux to be considered is 15-22 lmh. | |
| 70. |
What is the flux considered while designing a reverse osmosis system for treating surface water with UF system? |
| A. | 15-20 lmh |
| B. | 20-30 lmh |
| C. | 12-15 lmh |
| D. | 30-35 lmh |
| Answer» B. 20-30 lmh | |
| Explanation: the flux to treat surface water by a conventional method and to treat by uf differs. conventional method includes dual media filters. in case the surface water is treated by conventional, the flux considered should be around 20-30 lmh. | |
| 71. |
What do you mean by the term “Sorption”? |
| A. | attachment |
| B. | detachment |
| C. | diffusion |
| D. | thermal expansion |
| Answer» A. attachment | |
| Explanation: sorption is a physical and chemical process by which one substance becomes attached to another. the reverse of sorption is desorption. | |
| 72. |
The desorption curve is higher than the adsorption curve. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: theoretically, desorption curve is higher than adsorption curve in low pressure area if the material is mesoporous (2-50nm). if the material is microporous (<2nm), both curves should be matched together. | |
| 73. |
Which of the following isotherm is applicable to physical adsorption? |
| A. | langmuir |
| B. | bet |
| C. | freundlich |
| D. | kisluik |
| Answer» C. freundlich | |
| Explanation: the freundlich isotherm was the first isotherm model proposed for sorption processes. it can be applied for non ideal sorption on heterogeneous surfaces, as well as, multilayer sorption. a variation in the slope between 0 and 1 is associated with a chemisorption process, which is more heterogeneous as the value gets closer to 0. | |
| 74. |
Which type of isotherm is given from the figure, Choose from the following options? |
| A. | type 1 adsorption isotherm |
| B. | type 2 adsorption isotherm |
| C. | type 3 adsorption isotherm |
| D. | type 4 adsorption isotherm |
| Answer» A. type 1 adsorption isotherm | |
| Explanation: the above graph depicts monolayer adsorption. this graph can be easily explained using langmuir adsorption isotherm. examples of type-i adsorption are adsorption of nitrogen (n2) or hydrogen (h) on charcoal at temperature near to -1800c. | |
| 75. |
Which of the following statements regarding the physical adsorption of a gas on surface of solid is not correct? |
| A. | on increasing temperature, adsorption increases continuously |
| B. | enthalpy changes are negative |
| C. | adsorption is specific |
| D. | it is reversible in nature |
| Answer» A. on increasing temperature, adsorption increases continuously | |
| Explanation: physisorption is exothermic in nature. therefore according to le chateliars principle, it occurs readily at low temperature and decreases with increase in temperature. | |
| 76. |
Which of the following is not characteristic of chemisorption? |
| A. | it is irreversible |
| B. | it is specific |
| C. | it is multilayer phenomenon |
| D. | heat of adsorption is about 400kj |
| Answer» C. it is multilayer phenomenon | |
| Explanation: chemisorption involves formation of chemical bonds between adsorbate and adsorbent molecules. once the valency is satisfied, the adsorbent molecules can’t form bond with more adsorbate molecules. thus only one layer is formed. | |
| 77. |
For an adsorbant-adsorbate system obeying the Langmuir adsorption isotherm, b = 0.48 bar-1 and p = 0.16 bar-1. At what pressure will 50% of the surface be covered? |
| A. | 0.05 bar |
| B. | 0.07 bar |
| C. | 0.08 bar |
| D. | 0.04 bar |
| Answer» B. 0.07 bar | |
| Explanation: given data b = 0.48 bar-1 | |
| 78. |
Adsorption of methane follows the Langmuir adsorption isotherm at 90K. If p = 1.896cm3g-1bar-1 and b = 0.146bar-1. Calculate the value of θ. |
| A. | 0.116 bar |
| B. | 0.514 bar |
| C. | 0.214 bar |
| D. | 0.216 bar |
| Answer» D. 0.216 bar | |
| Explanation: given data p = 1.896cm3g-1 bar-1 | |
| 79. |
In Langmuir’s model of adsorption of a gas on a solid surface the mass of gas striking a given area of surface is to the pressure of the gas. |
| A. | proportional |
| B. | anti proportional |
| C. | independent |
| D. | none of the mentioned |
| Answer» A. proportional | |
| Explanation: in langmuir’s model of adsorption of a gas on a solid surface the mass of gas striking a given area of surface is proportional to the pressure of the gas. | |
| 80. |
The physical process that occurs when gas or liquid molecules are brought into contact with a solid surface and condense on the surface |
| A. | absorption |
| B. | adsorption |
| C. | both adsorption and absorption |
| D. | none of the mentioned |
| Answer» B. adsorption | |
| Explanation: adsorption is the physical process that occurs when gas or liquid molecules are brought into contact with a solid surface and condense on the surface. | |
| 81. |
Adsorption when interaction between the solid and the condensed molecules is relatively strong as contrasted with physical adsorption. |
| A. | absorption |
| B. | adsorption |
| C. | chemisorption |
| D. | none of the mentioned |
| Answer» B. adsorption | |
| Explanation: “chemisorption is the adsorption when interaction between the solid and the condensed molecules is relatively strong as contrasted with physical adsorption. | |
| 82. |
The gas molecules are held on solid surface by in physical adsorption. |
| A. | chemical forces |
| B. | gravitational forces |
| C. | electrostatic forces |
| D. | vander waal’s forces |
| Answer» D. vander waal’s forces | |
| Explanation: chemisorption is the adsorption when interaction between the solid and the condensed molecules is relatively strong as contrasted with physical adsorption. | |
| 83. |
The extent of adsorption of a gas on a solid depend on |
| A. | nature of gas |
| B. | pressure of gas |
| C. | temperature of the system |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: the extent of adsorption of a gas on a solid depend on all three nature of gas, pressure of gas and temperature of the system. | |
| 84. |
Which of the following gases is adsorbed by charcoal? |
| A. | nh3 |
| B. | h2 |
| C. | n2 |
| D. | co2 |
| Answer» A. nh3 | |
| Explanation: nh3 is easily liquefiable and highly water soluble gas. | |
| 85. |
Langmuir isotherm Mathematical relation for that takes place at equilibrium. |
| A. | absorption |
| B. | adsorption |
| C. | both adsorption and absorption |
| D. | none of the mentioned |
| Answer» B. adsorption | |
| Explanation: langmuir isotherm mathematical relation for adsorption that takes place at equilibrium. | |
| 86. |
Adsorption process must be |
| A. | endoethrgic |
| B. | endothermic |
| C. | exothermic |
| D. | none |
| Answer» C. exothermic | |
| Explanation: adsorption process is an exothermic process. | |
| 87. |
The rate law for a reaction between the substances A and B is given by rate = K[A]n [B]m. On doubling the concentration of A and halving the concentration of B. What will be the ratio of the new rate of the earlier rate of the reaction? |
| A. | ( 1 )m+n |
| B. | m2+n |
| C. | n-m |
| D. | 2n-m |
| Answer» D. 2n-m | |
| 88. |
On which factor the rate constant of a reaction does not depend upon? |
| A. | temperature |
| B. | activation energy |
| C. | catalyst |
| D. | concentration of reactants and products |
| Answer» D. concentration of reactants and products | |
| Explanation: the rate constant of reaction does not depend on concentration of reactant & product (only on nature of reactant & product). | |
| 89. |
The rate of reaction, A + B Products, is given by the equation, r = k[A][B]. If B is taken in excess, what would be the order of reaction? |
| A. | 2 |
| B. | 1 |
| C. | zero |
| D. | unpredictable |
| Answer» B. 1 | |
| Explanation: a + b → products | |
| 90. |
In a reaction, 2A2 + B2 → 2A2B, when the reactant A will disappear? |
| A. | half the rate that b will decrease |
| B. | the same rate that b will decrease |
| C. | double the rate that a2b will form |
| D. | twice the rate that b will decrease |
| Answer» D. twice the rate that b will decrease | |
| 91. |
The rate of reaction that does not involve gases, is not dependent on |
| A. | pressure |
| B. | temperature |
| C. | concentration |
| D. | catalyst |
| Answer» A. pressure | |
| Explanation: the rate of reaction that does not involve gases does not depend on pressure. | |
| 92. |
Which is not true for a second order reduction? |
| A. | it can have rate constant 1 x 10-2 l mol-1 s- 1 |
| B. | its half-life is inversely proportional to its initial concentration |
| C. | time to complete 75% reaction is twice of half-life |
| D. | t50 = 1/(ka⋅a0) |
| Answer» C. time to complete 75% reaction is twice of half-life | |
| 93. |
The rate of decomposition of a substance increases concentration of substance at same temperature. Find out order of reaction. |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 0 |
| Answer» B. 2 | |
| Explanation: rate = k [a]α r1 = k[a]n | |
| 94. |
Molecularity of a reaction is equal to the total number of |
| A. | products formed in the elementary step |
| B. | reactants taking part in elementary step |
| C. | reactants and products in the elementary step |
| D. | reactants and products in the final step |
| Answer» B. reactants taking part in elementary step | |
| Explanation: molecularity of a reaction is equal to the total number of reactants taking part in an elementary step. it is defined as the number of molecules or ions that participate in the rate determining step. | |
| 95. |
Which of the following statement is incorrect about the molecularity of a reaction? |
| A. | it is a theoretical concept |
| B. | each step of a multi-step reaction has a unique molecularity |
| C. | it is equal to the total number of reactants taking part in elementary step |
| D. | it can be zero, fractional or integer |
| Answer» D. it can be zero, fractional or integer | |
| Explanation: molecularity is always a whole number. it can be neither zero nor fractional. all the other options are correct. | |
| 96. |
Which of the following factor does not effect the rate of reaction? |
| A. | concentration of the reactant |
| B. | temperature |
| C. | pressure |
| D. | effect of catalyst |
| Answer» C. pressure | |
| Explanation: the reaction rate does not depend upon the pressure. it only depends upon the concentration of the reactant, temperature and effect of catalyst. | |
| 97. |
The reaction rate is greatly influenced by |
| A. | nature of bond in the reactant molecules |
| B. | strength of bond in the reactant molecules |
| C. | both nature and strength of the reactant molecules |
| D. | it does not depend on either nature or strength of the reactant molecules |
| Answer» C. both nature and strength of the reactant molecules | |
| Explanation: the reaction rate is greatly influenced by both nature and strength of the reactant molecules. reactants are the major factor that affects the rate of the reaction. | |
| 98. |
The reactions register an increase in rates in the presence of radiations of specific wavelengths. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: the reactions register an increase in rates in the presence of radiations of specific wavelengths. | |
| 99. |
Select the correct option from the following option. |
| A. | catalyst is used to increase the rate of reaction by altering chemically during the course of reaction |
| B. | catalyst is used to decrease the rate of reaction by altering chemically during the course of reaction |
| C. | catalyst is used to increase the rate of reaction and remains unaltered chemically during the course of reaction |
| D. | catalyst is used to decrease the rate of reaction and remains altered chemically during the course of reaction |
| Answer» C. catalyst is used to increase the rate of reaction and remains unaltered chemically during the course of reaction | |
| Explanation: catalyst is used to increase the rate of reaction and remains unaltered chemically during the course of the reaction. with a catalyst, reactions occur faster and require less activation energy. because catalysts are not consumed in the catalyzed reaction, they can continue to catalyze the reaction of further quantities of reactant. | |
| 100. |
Which of the following is not an adsorbent? |
| A. | carbon |
| B. | polymers and resins |
| C. | clay |
| D. | dry sponge |
| Answer» D. dry sponge | |
| Explanation: a sponge will absorb or take in water from another area and put it inside of itself. a dry sponge can hold more water than a wet sponge is closer to saturation and as such cannot hold more water. sponges with more tiny holes can absorb more water than the sponges with less tiny holes and thus leads to the absorption process. | |
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