Explore topic-wise InterviewSolutions in Current Affairs.

This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.

1.

For a reaction the graph drawn between t_(1//2) and a gives a straight line passing through the origin with the slope 2xx10^(2)"mole"^(-1) lit min. lf the initial concentation of the reactant is 1M, then the half life period is _______________X10^(2) min.

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Solution :`t_(1/2)=(C_(0))/(2xxK)impliest_(1/2)=(1/(2K))xxC_(0),t_(1/2)=(1xx4xx10^(2))/(2xx1),t_(1/2)=(4xx10^(2))/2=2xx10^(2)`
2.

For a reaction the following mechanism has been proposed , 2A+BtoD+E A+BtoC+D (slow), A+CtoE(fast) The rate law a expression for the reaction is

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`r=k[A]^(2)[B]`
`r=k[A][B]`
`r=k[A]^(2)`
`r=k[A][C]`

ANSWER :B
3.

For a reaction, the energy of activation is zero. What is the value of rate constant at 300 K, if k=1.6xx10^(6)s^(-1)" at 280 K ? "[R=8.31" JK"^(-1)mol^(-1)]

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SOLUTION :`E_(a)=0:.LOG""(k_(2))/(k_(1))=0" or "(k_(2))/(k_(1))=1" or "k_(2)=k_(1)`
4.

For a reaction the activation energy is zero. What is the value of rate constant at 300K. ["Given"k_(280K)=1.6xx10^(6)s^(-1),R=8.314J "mol"^(-1)K^(-1)]

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`2.08xx10^(-3)`
`2.08xx10^(-2)`
`6.93xx10^(-3)`
`6.93xx10^(-2)`

ANSWER :C
5.

For a reaction taking place in three steps, the rate constants are k_(1),k_(2) and k_(3). The overall rate constant is k=(k_(1)k_(2))/(k_(3)). If the energy of activation values for the first, second and third stages are 40, 50 and 60" kJ mol"^(-1) respectively, then the overall energy of activation in kJ mol"^(-1) is

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30
150
50
60

Solution :`K=(k_1k_3)/k_3`
`AE^(-E//RT)=(Ae^(-E_(1//RT))Ae^(-E_2//RT))/(Ae^(-E_3//RT))`
or`e^(-E//RT)=e^((-E_(1)-E_(2)+E_(3))//RT)`
or`-E/(RT)=(-E_1-E_2+E_3)/(RT)`
or`E=E_1+E_2-E_2=40+50-60`
`=30" kJ mol"^-1`
6.

Fora reaction taking place in three steps , the rate constants are k_(1) , k_(2) and k_(3) . The overall rate constant k = (k_(1) k_(2))/(k_(3)) . If the energy of activation values for the first , second and third stages are respectively 40 , 50 , and 60 kJ mol^(-1), then the overall energy of activation in kJ mol^(-1) is

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30
40
60
50

Answer :a
7.

For a reaction, temperature increases by 10^(@)C, the equilibrium will be attained faster

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2 times
same
`(1)/(2)` same
4 times

Solution :Rate of REACTION becomes almost twice with an increase of `10^(@)C` in TEMPERATURE (from 298 K to 308 K).
8.

For a reaction taking place is a container in equilibrium with its surroundings, the effect of temperature on its equilibrium constant K in terms of change in entropy is described by

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With increase in TEMPERATURE, the VALUE of K for endothermic reaction INCREASES because unfavourable change in entropy of the surroundings decreases
With increase in temperature, the value of K for exothermic reaction decreases because favourable change in entropy of the surroundings decreases
With increase in temperature, the value of K for exothermic reaction decreases because the entropy change of the system is positive
With increase in temperature, the value of K for endothermic reaction increases because the entropy change of the system is negative

Answer :A::B::C
9.

For a reaction taking place in a container in equilibrium with its surroundings, the effect of temperature on its equilibrium constant K in terms of change in entropy is described by

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With increase in TEMPERATURE, the value of K for endothermic REACTION increases because unfavourable CHANGE in ENTROPY of the surroundings decreases
With increase in temperature, the value of K for exothermic reaction decreases because FAVOURABLE change in entropy of the surroundings decreases
With increase in temperature, the value of K for endothermic reaction increases because the entropy change of the system is negative
With increase in temperature, the value of K for exothermic reaction decreases because the entropy change of the system is positive

Solution :`DeltaS_("Surr")=(-DeltaH)/(T_("Surr"))`
For endothermic, if `T_("surr")` increases, `DeltaS_("surr")` will increases.
For exothermic, if `T_("surr")` increases, `DeltaS_("surr")` will decreases.
10.

For a reaction taking place in a container inequilibrium with its surroundings the effect of temperature on its equilibrium constant K in terms of change in entrogy is described by

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with increase in temperature, the value of K for endothermic reaction increases beacouse unfavourable change in entrogy of the SURROUNDINGS DECREASES
With increase in temperature , the value of K for EXOTHERMIC REACTIONS decreause becacuse favourable change in entropy of the surrounding decreases
With increase in temperature, the value of K endothermic rection increases becouse the entrogy change of the system is negative
With increase in temperature, the value of K for endothemic reaction INCRESES because the entrogy change of the system is positive

Answer :a,b
11.

For a reaction t_(1//2)=[R]_(0)2k, reaction is of the

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FIRST ORDER.
SECOND order.
third order.
ZERO order.

ANSWER :D
12.

For a reaction represented by A rarr B, which of the following options do not given the value of order of the reaction. {:(A,ROR ="Rate of reaction",C="Concentration of reactant"),(,C_(0) ="Concentration of reactant",P="Concentration of product"),(B,t_(1//2) ="Half life of"A,):}

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`(log(ROR)_(2) - log(ROR)_(1))/(log C_(2)- log C_(1))`
`1+[(LOGT'_(1//2)-logt_(1//2))/(LOGC'_(0)-logC_(0))]`
Slope of In ROR us ln C GRAPH
y-intercept of log ROR us log C graph

Answer :D
13.

For a reaction Rate k=["acetone"]^(3//2) then unit of rate constant and rate of reaction respectively is ..........

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`(mol L ^(-1) s^(-1) ) , (mol ^(-1//2) L^(1//2)s^(-1))`
`(mol^(-1//2) L ^(1//2) s^(-1) ) , (MOLL^(-1)s^(-1))`
`(mol L s^(-1)),(mol^(1//2)L^(1//2)s)`
`(mol^(-1//2)s^(-1)),(molL^(-1)s^(-1))`

SOLUTION :Rate `=k[A]^N`
unit of rate `=(mol L ^(-1))/s = mol L ^(-1) s^(-1)`
unit of rat CONSTANT =`((mol L^(-1)s^(-1)))/((mol L ^(-1))^n)`
`= mol^(1-n) L^(n-1) s^(-1)`
in this case, rate `= k ["Acetone"]^(3//2)`
n = 3/2
`mol ^(1-(3//2)L^(3//2)s^(-1)`
`mol^(-(1//2)L^(1//2)s^(-1)`
14.

For a reaction Rate = "k [acetone]"^((3)/(2)) then unit of rate constant and rate of reaction respectively is

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`("mol "L^(-1)s^(-1)), ("mol"^(-1//2)L^(1//2)s^(-1))`
`("mol"^(-1//2)L^(1//2)s^(-1)), ("mol "L^(-1)s^(-1))`
`("mol"^(1//2)L^(1//2)s^(-1)), ("mol "L^(-1)s^(-1))`
`("mol "LS^(-1)), ("mol"^(1//2)L^(1//2)s)`

Solution :Rate `=K[A]^(n)`
Rate `=(-d[A])/(DT), " unit of rate"=("mol "L^(-1))/(s)="mol "L^(-1)s^(-1)`
unit of rate constant `=(("mol "L^(-1)s^(-1)))/(("mol "L^(-1))^(n))="mol"^(1-n)L^(n-1)s^(-1)`
In this CASE, rate `=k["Acetone"]^(3//2)`
`n=3//2`
`"mol"^(1-(3//2))L^((3//2)-1)s^(-1) rArr "mol"^(-(1//2))L^((1//2))s^(-1)`
15.

For a reaction R to P, half-life (t_(1//2)) is observed to be independent of concentration of reactants. What is the order of reaction ?

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SOLUTION :1 ST ORDER `(t_(1//2)=(0.693)/(K)).`
16.

For a reaction of the order of 0.5, when the concentration of the reactant is doubled, the rate

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doubles
increases FOUR times
decreases four times
increases `SQRT2` times

Answer :D
17.

For a reaction, Ox+ne^(-)tored, the neerst equation has a form of:

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`E=E^(@)+(RT)/(nF)ln([RED])/([OX])`
`E=E^(@)-(RT)/(nF)ln([red])/([Ox])`
`E=E^(@)-2.303(RT)/(nF)LOG([red])/([Ox])`
`E=E^(@)+(RT)/(nF)log([red])/([Ox])`

Answer :B::C
18.

For a reaction pA+qBto products the rate law expression is r=k[A]^(1)[B]^(m) then

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`(p+q)=(1+m)`
`(p+q)GT(1+m)`
`(p+q)` MAY or may not be equal to `(1+m)`
`(p+q)NE(1+m)`

ANSWER :C
19.

For a reaction of second order , t_(75%)=xt_(50%). The value of X is:

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Solution :For the second order reaction:
`t=1/k[1/[[A]]-1/[A]_(0)]`
For `t_(1//2)` or `t_(50%)`
`t_(50%) = 1/k[(1/[A]_(0))/2-1/[A]_(0)]=1/k[2/[A]_(0)-1/[A]_(0)]`
`=1/k xx 1/[A]_(0)`
For `t_(3//4)` or `t_(75%)`
`t_(75%) = 1/k[(1/[A]_(0))/4-1/[A]_(0)]=1/k[4/[A]_(0)-1/[A]_(0)]=1/k xx 3/[A]_(0)`
`t_(75%) = X t_(50%)`
`t_(75%)/(t_(50%))=(1/k xx 3/[A]_(0))/(1/k xx 1/[A]_(0))=3`
`THEREFORE x=3`
20.

For a reaction of II order kinetics, t_(1//_2) is:

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`PROP a`
`prop a^-3`
`prop a^2`
`prop a^-1`

ANSWER :D
21.

For a reaction nArarrB, following plots are given: The order of reaction for above plots are:

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`1,0,2`
`0,1,2`
`1,1,2`
`0,2,1`

SOLUTION :`(d[A])/(dt)=K.[A],` for FIRST ORDER reaction
`[A]=[A]_(0)-kt,` for zero order reaction
`1/([A]_(t))=1/([A]_(0))+kt` for SECOND order reaction
22.

For a reaction NO_(g) +O_(2) (g)rarr 2NO_(2)(g) Rate=k[NO^(2)] [O_(2)] if the volume of the reaction vessel is doubled the rate of the reaction :

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will diminish to 1/4 of initial value
will diminish to 1/8 of initial value will grow 4 times
will grow 4times
will grow 8 times

SOLUTION :(B) On increasing the volume to twice the value the concentration of each species is REDUCED by a factor of 2 . Therefore
RATE = `k[NO]^(2) [O_(2)]`
`"Rate"_(2)= k(([NO])/(2))^(2)(([O_(2)])/(2))`
`("Rate"_(2))/("Rate"_(1)) = (1)/(8)`
23.

For a reaction, N_(2)(g)+3H_(2)(g)rarr 2NH_(3)g),identify dihydrogen (H_(2)) as a limiting reagent in the following reaction mixtures.

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`"56 G of "N_(2)+"10 g of "H_(2)`
`"35 g of "N_(2)+"8 g of "H_(2)`
`"28 g of "N_(2)+"6 g of "H_(2)`
`"14 g of "N_(2)+"4 g of "H_(2)`

Solution :According to the stoichiometry of balanced equation `28g N_(2)` react with `6gH_(2)`
`underset("28g")underset("1 mole")(N_(2))+underset("6g")underset("3 mole")(3H_(2))RARR 2NH_(3)`
`therefore"For 56 g of "N_(2), 12 g " of " H_(2)` is required.
24.

For a reaction, N_(2)(g) + 3H_(2)(g) to 2NH_(3)(g) , identify dihtdrogen (H_(2)) as a limiting reagent in the following reaction mixtures.

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`14G of N_(2) + 4G of H_(2)`
`28g of N_(2) + 6G of H_(2)`
`56g of N_(2) + 10g of H_(2)`
`35G of N_(2) + 8g of H_(2)`

Answer :C
25.

For a reaction, K=2xx10^(13)e^(-30000//RT). When log K (y-axis) is ploted against 1/T (x-axis) slope of line be. . . ..Cal

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`(30000)/(4.6)`
`(-30000)/(4.6)`
`(-30000)/(2.3030)`
`(-30000)/(4.6)`

ANSWER :D
26.

For a reaction(K_((1+10)))/(K_((1)))=x. When temperature is increased from 10^(@)C to 100^(@)C rate constnat (K) increased by a factor of 512. Then value of x is

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`1.5`
`2.5`
`3`
`2`

ANSWER :D
27.

For a reaction involving 1 mol of Zn and 1 mol of H_(2)SO_(4) in a bomb calorimeter-

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`DELTAU GT0, W gt0`
`DeltaU gt0,w=0`
`DeltaU LT0,w lt0`
`DeltaU lt0,w=0`

ANSWER :D
28.

For a reaction k is 2.5 xx 10^(-3) 1/(mol xx sec). The order of reaction is

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half
one
two
three

Solution :UNIT of 'k' for the REACTION is L `mol^(-1) SEC^(-1)` which represents a second order reaction.
29.

For a reaction K=2xx10^-2 mole lit^-1 sec^-1. If the concentration of the reactant is IM, the half life period of the reaction is

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20 sec
25 sec
34.6 sec
50 sec

Answer :B
30.

Fora reaction in gaseous state to reach an equilibrium state the reaction should be carried out in

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An OPEN vessel
Closed vessel
Glass vessel
Iron vessel

Answer :B
31.

For a reaction in a galvanic cell the value of -DeltaG^(@) at certain temperatureis not necessarily equal to

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`nFE^(@)`
`RT LN K `
` T. DeltaS^(@) - DELTAH^(@)`
Zero

Solution :`DeltaG = -2.303RT log K , DeltaG^(0) = 0` at EQUILIBRIUM
32.

For a reaction if k_(p)gtk_(c) the forward reaction is favoured by

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LOW PRESSURE
hifh pressure
HIGH temperature
Low temperature

Answer :A
33.

For a reaction having rate law expression : Rate = k[A]^(3//2) [B]^(-1//2) If the concentration of both A and B become four times the rate of reaction

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become FOUR times
becomes 16 times
DECREASES four times
reamains same .

Solution :(A) `r_(1)=k (a)^(3//2)(b)^(-1//2)`
`r_(2) = k (4a)^(3//2)(4b)^(-1//2)`
`(r_(2))/(r_(1))=(4)^(3//2)(4)^(-1//2)=4 ` .
34.

For a reaction: HX(aq) + H_2O

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`CLO^(-)`
`F^(-)`
`Cl^(-)`
`NO_(2)^(-)`

ANSWER :C
35.

For a reaction if K_(p) gt K_(c), the forward reaction is favoured by

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A) LOW PRESSURE
B) HIGH pressure
C) high temperature
D) low temperature

Solution :Low pressure.
36.

For a reaction, H_2O_2rarrH_2O_2+1//2O_2 ({d [H_2O_2])}/{dt}=K_1[H_2O_2], (d[H_2O_2])/dt=K_2[H_2O],(d[O_2])dt=K_3[H_2O_2] Therelationbetween K_1, K_2 and K_3is

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(a) `K_1=K_2=K_3`
(B) `K_1=K_2=2K_3`
(C) `2K_1=4K_2=K_3`
(d) `2K_1=2K_2=K_3`

ANSWER :B
37.

For a reaction : H_(2)+Cl_(2) underset("Rate"=k)(overset(hv)to 2HCl) (i) Write the order and molecularity of this reaction. (ii) Write the unit of k.

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Solution :(i) When rate of the reaction is equal to k, that means it is reaction of ZERO ORDER. THUS
Order = 0 (zero)
Molecularity = 2
(ii) As k = rate and the UNITS of rate are moles `L^(-1)s^(-1)`. Therefore units of `k="mol L"^(-1)s^(-1)`.
38.

For a reaction DeltaH = 9.08 kJ mol^(-1) and DeltaS=35.7 JK^(-1)mol^(-1) Which of the following statements is correct for the reaction

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REVERSIBLE and Isothermal
Reversible and Exothermic
Spontaneous and Endothermic
Spontaneous and Exothermic

Solution :`DELTAH` and `DeltaS` both are +ve for spontaneous CHANGE, and `DeltaH=+ve` for endothermic REACTION.
39.

For a reaction, H_2+I_2hArr 2HI at 721 K , the value of equilibrium constant is 50. If 0.5 moles each of H_2 and I_2 is added to the system the value of equilibrium constant will be :

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40
60
50
30

Solution :The EQULIBRIUM constant does not CHANGE when concentration of reactant is CHANGED as the concentration of PRODUCT also get changed accordingly.
40.

For a reaction for which the activation energies of forward and reverse reactions are equal:

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`DeltaH=O`
`DeltaS=O`
The ORDER is zero
There is no catalyst

Answer :A
41.

For a reaction DeltaH=(+3kJ), DeltaS=(+10J//K)beyond which temperature this reaction will be spontaneous

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300 K
200 K
273 K
373 K

Solution :`DeltaG=DeltaH-TDeltaS`.
For the SPONTANEOUS REACTION the `DeltaG` MUST be NEGATIVE.
`DeltaH=3kJ=+3000 J`
`DeltaS=+10 J//K`
If `T=300 K implies DeltaG=3000-300xx10=0`
If `T=200 K implies DeltaG=3000-200xx10=1000 J`
If `T=273 K implies DeltaG=3000-273xx10=270 J`
If T = 373 K
`DeltaG=3000-373xx10=-730 J`
Hence, beyond 373 temperature the reaction will be spontaneous.
42.

For a reaction C(s)+CO_(2)(g)hArr2CO(g)

Answer»

The equlibrium shifts in backward direction if more of CO is added
The equilibrium shifts in backward direction if more of CO is added
The equlibrium shifts in forward direction if more of corbon is added
On adding carbon, the equlibrium is not disturbed

SOLUTION :`Q_(p)=(P_(CO)^(2))/(P_(CO_(2))),Q_(C)=([CO]^(2))/([CO_(2)])`
When more of `CO_(2)` is added `Q_(p)` DECREASES, hence in order to reach equlibrium, SYSTEM moves in forward direction, hence choice (a) is correct.
When more of CO is added, `Q_(p)` increases and therefore to reach equlibrium, system moves in backward DIRECTIN, so choice (b) is correct.
Since active mass of colids is 1, hence changing the concentrations of carbon does not change Q. Hence adding carbon does not shift the equlibrium, (c) is incorrect. Whereas (d) is correct.
43.

For a reaction [CaCO_3(s) implies CaO(s) + CO_2(g)] (K_c = 0.5 moll^-1), the maximum moles of CO_2(g) formed at equilibrium in 5 L container is

Answer»

5
2.5
1.24
10

Answer :4
44.

For the raction A+Brarr products, it is found that order of A is 2 and the order of B is 3. In the rate expression when the concentration of both A and B are doubled the rate will increases by a factor

Answer»

12
16
32
10

Solution :Given `"Rate"_(1st) = K[A]^(2) [B]^(3) "" … (i)`
`"Rate"_(2nd) = K[2A]^(2) [2B]^(3) "" …. (ii)`
On DIVIDING equation (i) and (ii) we get
`("Rate"_(1st) )/("Rate"_(2nd)) = (K[A]^(2)[B]^(3))/(K4[A]^(2)8[B]^(3)) = (1)/(32)`
`therefore "Rate"_(2nd) = 32 XX "Rate"_(1st)`
45.

For a reaction AtoB, the rate of reaction can be denoted by -(dA)/(dt)" or "+(dB)/(dt). State the significance of plus and minus signs in this case.

Answer»

Solution :Rate of reaction is always positive. Minus SIGN INDICATES decrease in the concentration of the reactant, i.e., `d[A]` is -ve so that `(-)xx(-)=+"ve"`. PLUS sign indicates INCREASE in the concentration of the product with time during the reaction, i.e., `d[B]` is + ve.
46.

For a reaction AtoB, E_(a) = 10kJ mol^(-1) and DeltaH = 5 kJmol^(-1). Which is correct potential energy profile for the reaction?

Answer»

Solution :II is the CORRECT POTENTIAL ENERGY profile for the reaction which is of endothermic nature.
47.

For a reaction AtoB+C. It was found that at the end of 10 minutes from the start.The total optical rotation of the system was 50^(@) and when the reaction is complete it qws 100^(@). Assume that only B and C are optically active and dextro rotatory, the rate constant of this first order reaction wouldbe

Answer»

`6.9"min"^(-1)`
`0.069"min"^(-1)`
`0.69"min"^(-1)`
`6.9xx10^(-2)"min"^(-2)`

Solution :`[C_(0)-X[x""x`
`0""C_(0)""C_(0)`
`C_(0)alpha50,xoo25.K=2.303/10xxlog(50/25)=(2.30xx0.3010)/10=0.693/10=0.0693"min"^(-1)`
48.

For a reaction Ato products, the graph drawn between rate of reaction Vs (a-x) gives a straight line with the slope 0.0693 "min"^(-1).Initial concentration of the reactant is 0.4M . After 20 minutes the rate of reaction is calculated as 6.93xx10^(-x). Report the value of x?

Answer»


Solution :`r=K.(a-x)^(N)impliesn=1,r=K(a-x),0.0693xx20=2.303xx"log"(0.4/(Ct))`
`2xx0.3010=log(0.4/(Ct)),4=0.4/(C_(t))impliesC_(t)=0.1,r=K.(C_(t))^(1)=0.693xx(0.1)^(1)=6.93xx10^(-3)`
49.

For a reaction Ato products, the rate of reaction is increased by 8 times when the concentration of A is doubled then

Answer»

order of the reaction is 4
order of the reaction is 3
units of rate constant are `"mole"^(-2)"LIT"^(2)"TIME"^(-1)`
rate `=K[A]^(3)`

Solution :`r=K[A]^(3),M/t=Kxx(M)^(3)impliesK=M^(-2)"time"^(-1)`
50.

For a reaction Ato products, half life is 40 min, when the initial concentration of A is 4 molar. Half life of same reaction is 80 mm when the initial concentration orf A is 2 molar. Then

Answer»

order is 1
order of the REACTION is 2
units of rate constant is `"time"^(-1)`
unit of rate of reaction MOLE `"LIT"^(-1)"time"^(-1)`

Solution :`[A]_(0)""4""2`
`t_(1/2)""40""80`
`((t_(1/2))_(1))/((t_(1/2))_(2))=((C_(2))/(C_(1)))^((n-1)),(40/80)=(2/4)^((n-1)),(1/2)^(1)=(1/2)^(n-1),1=n-1,n=2`