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91001.

(A) Ce^(4+) is used as an oxidising agent in volumetric analysis. (R) Ce^(4+) has a tendency to attain a stable + 3 oxidation state

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Both (A) and (R) are TRUE and (R) is the CORRECT EXPLANATION of (A)
Both (A) and (R) are true and (R) is not the correct explanation of (A)
(A) is true but (R) is FALSE
Both (A) and (R) are false

Solution :Both (A) and (R) are true and (R) is the correct explanation of (A)
91002.

(A): Ce^(4+) is a good oxidizing agent. (R): Sm^(2+) is a good reducing agent.

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Both A & R are TRUE, R is the correct EXPLANATION of A
Both A & R are true, R is not correct explanation of A
A is true, R is FALSE
A is false, R is true

Answer :B
91003.

A : ccp is more efficient than hcp. R : Packing fraction is different in both cases.

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If both ASSERTION & REASON are true and the reason is the correct explanation of the assertion then MARK (1)
If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
If Assertion is true STATEMENT but Reason is false then mark (3)
If both Assertion and Reason are false STATEMENTS, then mark (4)

Answer :D
91004.

(A) : CdS and As_(2)S_(3) both have yellow colour and precipitated by passing H_(2)S through solution in dil HCl. ® : Both can be separated by yellow ammonium sulphide.

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Solution :`Cd^(2+)` BELONGS to group IIA
`As^(3+)` belongs to group IIB
91005.

A cation M^(3+) loses 3 electrons, its oxidation number becomes

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`M^(6+)`
`M^(1+)`
`M^(2+)`
`M^(5+)`

ANSWER :D
91006.

(A) Cation carriers, e.g., H-Br,Cl-OH and Br-Br and oxidising agents such as O_(3) and R-O-O-R, etc. act as electrophilic reagents. (R) Electrophilec are Lewisbases.

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If both (A) and(R) are CORRECT and (R) is the correct EXPLANATION of (A).
If both (A) and (R) are correct but (R) is not the correct explanation of (A).
If (A) is correct but (R) is INCORRECT.
IF (A) is incorrect but (R) is correct.

Answer :B
91007.

(A): Catanation ability of sulphur is observed in polysulphides (R): A polysulphide with eight sulphur atoms is known

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Both (A) and (R ) are true and (R ) is the correct EXPLANATION of (A)
Both (A) and (R ) are true and (R ) is not the correct explanation of (A)
(A) is true but (R ) is FALSE
Both (A) and (R )are false

Answer :C
91008.

A catayst

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INCREASES the average KINETIC ENERGY of reacting molecules
Increases the activation energy
Alters the reaction mechanism
Increases the FREQUENCY of collisions of reacting species

Answer :C
91009.

A catalytic poison renders the catalyst ineffective because :

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It is PREFERENTIALLY adsorbed on the catalyst
It adsorbs the molecules of the reactants
It COMBINES CHEMICALLY with the catalyst
It combines with one of the reactants

ANSWER :A
91010.

A catalyst that can be employed for Friedel-Crafts acylation is

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anhydrous `CuCl_(2)`
anhydrous `BCl_(3)`
anhydrous `CaCl_(2)`
HYDRATED `AlCl_(3)`

Solution :Anhyd. `BCl_(3)` is a LEWIS acid but hydrated `AlCl_(3)` is not.
91011.

A catalyst speeds up a chemical reaction by :

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SHIFTING the equilibrium.
increasing the ACTIVATION energy.
decreasing the REACTION enthalpy.
providing an ALTERNATIVE enthalpy.

Answer :A
91012.

A catalyst lowers the activation energy of a reaction in such a manner that rate constant at 27^(@) C uncatalysed reaction equals the rate constant at ._(-73^(@) Cfor cataysed reaction . By how many kJ activation energy barrier is reduced by catalyst? Activation energy for the reaction is 24kJ.

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ANSWER :8
91013.

A catalyst lowers the activation energy of a reaction from 20 kJ mol^(-1) to 10 kJ mol^(-1). The temperature at which uncatalysed reaction will have same rate as that of catalysed at 27°C is

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327°C
283°C
445°C
600°C

Answer :A
91014.

A catalyst lowers the activation energy for a certain reaction from 83.314 to 75 KJ "mol"^(-1) at 500 K . What will be the rate of reaction as compared to uncatalyst reaction ? Assume other things being equal

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Double
28 TIMES
7.38 times
`7.38 XX 10^(3)` times

Answer :C
91015.

A catalyst is used in a reaction to :

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CHANGE the NATURE of reaction products
Increases the reaction yield
Decrease the need for reactants
Decrease the time REQUIRED for the reaction

Answer :D
91016.

A catalyst is used

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only for increasing the velocity of reaction.
for altering the velocity of reaction.
only for decreasing the velocity of reaction.
for GETTING greater yield of the PRODUCT.

ANSWER :B
91017.

A catalyst is more effective in :

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FINELY POWDERED state
Colloidal state
Rough surface
All

Answer :D
91018.

A catalyst is a substance which enhances the rate of a chemical reaction without itself getting____________ in the reaction.

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SOLUTION :USED up
91019.

A catalyst is a substance which

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INCREASES the equilibrium concentration of the product
changes the equilibrium constant of the reaction
shortens the time to REACH equilibrium
supplies energy to the reaction

Solution :shortens the time to reach equilibrium
91020.

A catalyst is a substance which:

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Increases the equilibrium concentration of the REACTION
Change the equlibibrium constant of the reaction
Shortest the TIME to reach equilibrium
Supplies energy to the reaction

Solution :Because CATALYSIS enhances the rate of reaction.
91021.

A catalyst is a substance which :

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Alters the EQUILIBRIUM in a REACTION
Does not participate in the reaction but speeds it up
Participates in the reaction and provides at easier PATHWAY for the same
Is always in the same phase as the reactants

Answer :C
91022.

A catalystincreases therateof thetemperature

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INCREASING `E_(a)`
increasingT
DECREASING `E_(a)`
decreasingT

Solution :EFFECT of CATALYST.
91023.

A catalyst increases the rate of reaction because it…

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INCREASES the activation energy
decreases the energy BARRIER for reaction
decreases the collision diameter
increases the TEMPERATURE coefficient.

Answer :B
91024.

A catalyst increases the rate of the reaction by

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INCREASING`E_(a)`
increasing T
DECREASING `E_(a)`
decreasing T

ANSWER :A::C::D
91025.

A catalyst increases the rate of reaction because it:

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Increases the activation energy
DECREASES the energy barrier for reaction
Decreases the COLLISION diameter
Increases the TEMPERATURE COEFFICIENT

Answer :B
91026.

A catalyst increases the rate of chemical reaction by providing an alternative reaction pathway which lowers the activation energy than the reaction pathway in its absence. A catalyst is not consumed and therefore does not appear in the chemical equation for the reaction. A homogenous catalyst is in the same phase as the ractants whilst a heterogeneous catalyst is in a different phase. The complex [Co(NH_(3))_(3)F]^(2+)+H_(2)Oto[Co(NH_(3))_(5)(H_(2)O+F^(-)]^(3+) and Rate =k["complex"]^(a).[H^(+)]^(b) The reaction is acid catalysed , i.e. [H^(+)] does not change during the reaction . Thus, rate =k'["complex"] where, k'=[H^(+)]^(b) The value of activation energy for a chemical reaction primarily depends on

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temperature
nature of REACTING species
collision frequency
concentration of reactants

Answer :B
91027.

A catalyst increases the rate of chemical reaction by providing an alternative reaction pathway which lowers the activation energy than the reaction pathway in its absence. A catalyst is not consumed and therefore does not appear in the chemical equation for the reaction. A homogenous catalyst is in the same phase as the ractants whilst a heterogeneous catalyst is in a different phase. The complex [Co(NH_(3))_(3)F]^(2+)+H_(2)Oto[Co(NH_(3))_(5)(H_(2)O)+F^(-)]^(3+) and Rate =k["complex"]^(a).[H^(+)]^(b) The reaction is acid catalysed , i.e. [H^(+)] does not change during the reaction . Thus, rate =k'["complex"] where, k'=[H^(+)]^(b) If 'a' is the initial concentration and k is the rate constant of a zero order reaction , the time for the reaction to go to completion will be

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`(K)/(a)`
`(a)/(k)`
`(a)/(2K)`
`(k)/(2A)`

ANSWER :B
91028.

A catalyst increases the rate of reaction because it :

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decreases the ACTIVATION energy
Decreases the energy barrier for reaction
Decreases the COLLISION diameter
Increases the temperature coefficient

Answer :C
91029.

A catalyst increases the rate of chemical reaction by providing an alternative reaction pathway which lowers the activation energy than the reaction pathway in its absence. A catalyst is not consumed and therefore does not appear in the chemical equation for the reaction. A homogenous catalyst is in the same phase as the ractants whilst a heterogeneous catalyst is in a different phase. The complex [Co(NH_(3))_(3)F]^(2+)+H_(2)Oto[Co(NH_(3))_(5)(H_(2)O+F^(-)]^(3+) and Rate =k["complex"]^(a).[H^(+)]^(b) The reaction is acid catalysed , i.e. [H^(+)] does not change during the reaction . Thus, rate =k'["complex"] where, k'=[H^(+)]^(b) Overall order of reaction is

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`1`
`2`
`0`
`(1)/(2)`

ANSWER :B
91030.

A catalyst increases the rate of chemical reaction by providing an alternative reaction pathway which lowers the activation energy than the reaction pathway in its absence. A catalyst is not consumed and therefore does not appear in the chemical equation for the reaction. A homogenous catalyst is in the same phase as the ractants whilst a heterogeneous catalyst is in a different phase. The complex [Co(NH_(3))_(3)F]^(2+)+H_(2)Oto[Co(NH_(3))_(5)(H_(2)O+F^(-)]^(3+) and Rate =k["complex"]^(a).[H^(+)]^(b) The reaction is acid catalysed , i.e. [H^(+)] does not change during the reaction . Thus, rate =k'["complex"] where, k'=[H^(+)]^(b) For the reaction , CH_(3)COCH_(3)+I_(2)overset(H^(+))(to) Products The rate is governed by the expression (dx)/(dt)=k["Acetone"][H^(+)] The order w.r.t. iodine is

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`0`
`1`
`2`
`3`

ANSWER :A
91031.

A catalyst increases the rate of chemical reaction by providing an alternative reaction pathway which lowers the activation energy than the reaction pathway in its absence. A catalyst is not consumed and therefore does not appear in the chemical equation for the reaction. A homogenous catalyst is in the same phase as the ractants whilst a heterogeneous catalyst is in a different phase. The complex [Co(NH_(3))_(3)F]^(2+)+H_(2)Oto[Co(NH_(3))_(5)(H_(2)O+F^(-)]^(3+) and Rate =k["complex"]^(a).[H^(+)]^(b) The reaction is acid catalysed , i.e. [H^(+)] does not change during the reaction . Thus, rate =k'["complex"] where, k'=[H^(+)]^(b) From the above data, value of a is :

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`1`
`2`
`0`
`(1)/(2)`

ANSWER :A
91032.

A catalyst increases the rate of a reaction with out changing ______

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energy of activation 
HEAT of the reaction 
PATH of reaction 
Mechanism of reaction 

ANSWER :B
91033.

A catalyst increases the rate of a chemical reaction by

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Increasing the ACTIVATION ENERGY
Decreasing the activation energy
Reacting with REACTANTS
Reacting with products

SOLUTION :Catalyst increases the rate by decreasing the activation energy.
91034.

A catalyst increases rate of reaction by

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DECREASING ENTHALPY.
decreasing internal ENERGY.
decreasing ACTIVATION energy.
INCREASING activation energy.

Answer :C
91035.

A catalyst increase rate of reaction by

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decrease enthalpy.
DECREASING internal ENERGY .
decreasing activation energy.
increasing activation energy.

Solution :Activation energy is LOWERED in PRESENCE of +ve catalyst.
91036.

A catalyst in the finely divided from is most effective because :

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Less surface area is available
More active CENTRES are formed
More energy GETS STORED in the catalyst
None

Answer :B
91037.

A catalyst has no effect on

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RATE of FORWARD reaction
activation energy
thershold energy
heat of reaction

Answer :D
91038.

A catalyst in a chemical reaction does not change

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Average ENERGY of reactants or products
ENTHALPY of the REACTION
ACTIVATION energy of the reaction
Both 1 and 2

Answer :D
91039.

A catalyst for reversible reaction is a substance that :

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Supplies ENERGY to the reaction
Decreases the TIME to reach equilibrium
Increases the equilibrium concentration of the products
Change the equilibrium CONSTANT of the reaction

Answer :B
91040.

A catalyst do not change :

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GIBBS ENERGY of REACTION
enthalpy of reaction
equilibrium constant
Activation energy of reaction

Answer :A::B::C
91041.

A catalyst always increases the rate of reaction.

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91042.

A catalyst alters the rate of a reaction by leading of increasing the energy of activation, In Heterogeneus catalysis adrosption mechanism occurs and Hemogeneus. Catalysis intermediate formation occurs. In auto catalysis one of the products acts on catalyst. AsH_3 to As + 3H_2. The reaction is auto catalysed. Which graph is correct for it?

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Solution :In AUTO catalysis first REACTION is SLOW after some time reaction is FAST
91043.

A catalyst alters the rate of a reaction by leading of increasing the energy of activation, In Heterogeneus catalysis adrosption mechanism occurs and Hemogeneus. Catalysis intermediate formation occurs. In auto catalysis one of the products acts on catalyst. 2SO_2 + O_(2) overset(NO(g))(rarr)2SO_3. This reaction is carried out through formation of ----- intermediate.

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`N_2O`
`NO_2`
`N_2O_4`
`N_2O_3`

SOLUTION :`2NO + O_2 to 2NO_2`
`NO_2 + SO_2 to SO_3 + NO` INTERMEDIATE is `NO_2`
91044.

A catalyst alters the rate of a reaction by leading of increasing the energy of activation, In Heterogeneus catalysis adrosption mechanism occurs and Hemogeneus. Catalysis intermediate formation occurs. In auto catalysis one of the products acts on catalyst. The DeltaH of a reaction A + B to C is d-20 KJ mol^(-1). When a catalyst is used. What is DeltaH for the reaction without catalyst (magnitude)

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`lt 20 KJ`
`gt 20 KJ `
`20 KJ `
Depends on CATALYST 

SOLUTION :Catalyst does not change `DELTAH` of the reaction
91045.

A catalyst accelerates the reaction, because

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it brings the reactants closer
it lowers the activation energy
it CHANGES the HEAT of reaction
it INCREASES the activation energy

Answer :B
91046.

A catalyst :

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Increases the average kinetic energy of reacting molecules
DECREASES the activation energy
Alters the reaction mechanism
Increases the FREQUENCY of COLLISIONS of reacting SPECIES

Solution :A catalyst provides the path of LOWER activation energy . The catalyst reacts with the reactions to form an intermediate of low activation energy . The intermediate then decomposes to form the product along with regeneratoin of catalyst . Thus the reaction mechanism changes completely .
91047.

A catalyst:

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INCREASES the AVERAGE kinetic ENERGY of reacting molecules.
DECREASES the activation energy
alters the reaction mechanism
increases the frequency of collisions of reacting species.

Solution :(b.c) A catalyst decreases activation energy Alters the reaction mechanism.
91048.

(A) : Cassiterite mineral is concentrated by electromagnetic method (R): Tinstone is non-magnetic and impurity wolframite is magnetic

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Both A & R are true, R is the correct EXPLANATION of A
Both A & R are true, R is not correct explanation of A
A is true, R is FALSE
A is false, R is true

Answer :A
91049.

(A) Cassiterite mineral is concentrated byelectromagnetic method (R) Tinstoneis non-magnetic and impurity wolframite is magnetic

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Both (A) and (R) are true and (R) is the correct explanation of (A)
Both (A) and (R) are true and (R) is not the correct explanationof (A)
(A) is true but (R) is FALSE
Both (A) and (R) are false

ANSWER :A
91050.

A Carnot engine operates between temperatures 600 K and 390 K. Ir absorbs 120 cal of heat from the source. Calculate eta and the heat rejected to the sink.

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SOLUTION :We have `eta=(T_(2)-T_(1))/(T_(2))=(600-390)/(600)=0.25` or `25%`
Now, again we have,
`eta=(W)/(q_(2))=(q_(2)-q_(1))/(q_(2))`
where `q_(2)` is the HEAT absorbed by the system from the source and `q_(1)` is the heat rejected to the sink.
`:.(120-q_(1))/(120)=0.25`
`:.q_(1)=90` cal