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 gaseous reaction 2A+B_(2)to2AB, the following rate data were obtained at 300 K {:("Rate of disappearance of "B_(2),,,"""Concentration",,,),("(""mol lit"^(-1)"min"^(-1)")",,,[A],,,[B_(2)]),((i)1.8xx10^(-3),,,0.015,,,0.15),((ii)1.08xx10^(-2),,,0.09,,,0.15),((iii)5.4xx10^(-3),,,0.015,,,0.45):} Calculate the rate constant for the reaction and rate of formation of AB when [A] is 0.02 and [B_(2)] is 0.04 "mol lit"^(-1)" at 300 K".

Answer»


Solution :From (i) and (II), when `[B_(2)]` is KEPT constant and [A] is made 6 times, the rate also six times. Thous, Rate `prop[A].` Further, from (i) and (iii), when [A] is kept constant and `[B_(2)]` is made three times, rale also becomes three times. Thus, Rate `prop[B_(2)]`. Hence, rate `=k[A][B_(2)].` PUT the values of [A] and `[B_(2)]` and calculate k. It comes out to be 0.8 LITRE `"mol"^(-1)min^(-1)`. When [A] = 0.02 M and `B_(2)=0.04" M",`
Rate of formation of `AB=2xx" Rate of disappearance of "B_(2)`
2.

For a gas-solid system, classical adsorption isotherm is applicable. If mg of solid adsorb xg of gas at pressure p, then which of the following plots will be a straight line?

Answer»

<P>`x/m vs.p`
`P/(x//m)Vs.`
`logx_m Vs.`
`logx_M Vs.`

SOLUTION :It is according to Freundlich adsorption ISOTHERM `log""x/3 g+1/n log `
3.

For a gaseous equilibrium, A +2B hArr C + 3D the partial pressures of A, B, C and D are found to be 0.20, 0.10, 0.30 and 0.50 atm respectively. Predict the value of equilibrium constant.

Answer»

11.25
18.75
5
3.75

Answer :B
4.

Fora gas - solidadsorbentsystem, theadsorptionisotherm (x)/(m) = kp^(1//m) is applicable , where n=5in the specifiedcase . Select the correctstatement.

Answer»

`(x)/(m)` vs p plotis a linear graph with slope EQUAL to 5.
`LOG (x)/(m)` vs logp plot is a straight line with slopeequal to 5.
`log (x)/(m)` vs log p is a straightline withslopeequal to 0.2.
None of these

SOLUTION :Slope`= (1)/(N) = (1)/(5) = 0.2`
5.

For a gas reaction ArarrP at T (K) the rate is given by : Rate=k^(') p_(A)^(2) atm/hr

Answer»
6.

For a gas phasereaction , the unit of reaction rat is .......

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`s^(-1)`
`"ATM " s^(-1)`
`MOL L^(-1)s^(-1)`
`mol^(-1)L^(-1)s^(-1)`

Answer :B
7.

For a gas (R//C_(v)) = 0.67, the gas is made up of molecules which are

Answer»

Polyatomic
Mixture of GAS
Diatomic
Monatomic

Answer :D
8.

For a gas ((R)/(C_v)) = 0.67, the gas is made up of molecule which are :

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Monoatomic
Diatomic
Polyatomic
Mixture of gases

Answer :A
9.

For a gas at room temperature (289 K)and 1 atm, each molecules undergoes approximately ............ Per second.

Answer»

SOLUTION :`10^9` COLLISIONS
10.

For a fixes amount of real gas when a graph of z v//s was plotted than at very high pressure slope was observed to be 0.01 atm^(-1). At the same temperature if a graph is plotted b//w pv v//s P then for 2 moles of the gas 'Y' intercept is found to be 40 atm-litre. calculate excluded volume in litres for 20 moles of the real gas.

Answer»


Solution :`:.` very high pressure `:.` NEGLECT (a)
`:. Z = 1+(Pb)/(RT) ..(1)`
comparing above equation with `y = mx +c`
`:. M = (b)/(RT)`
`rArr (b)/(RT) = 0.01` (GIVEN `m = 0.01)`
`b = 0.01 RT ..(2)`
`Z = ((PV)_(real))/((PV)_("ideal"))` ltbr. `Z = ((PV)_(real))/(nRT)` (given for `N = 2, PV = 40)`
`Z = (40)/(2RT)`
`Z (20)/(RT) ...(3)`
as, `Z = 1+(Pb)/(RT)`
from equation (3)
`(20)/(RT) = 1+(Pb)/(RT) ..(4)`
`10 = RT +Pb`
`Pb = 20 - RT ...(5)`
`(PV)_(real) = 40= ZnRT = (1+(Pb)/(2RT)) 2RT`
`rArr 40 = (1+(20-RT)/(2RT)) 2RT`
`40 = 2RT +20 - RT`
`20 = RT...(6)`
From (2) & (4)
`b = 0.01 xx 20`
`b = 0.2`
excluded volume for 20 moles
`nb = 20 xx 0.2`
`nb = 4`
11.

For a fixed amount of an ideal gas P us T plot is given as shown. Identify the correct option.

Answer»

The change from A to B should be isochoric
VOLUME first INCREASES reached MAXIMA and then decreases
`PV = NRT` is not applicable
None of the statements are correct

Answer :D
12.

For a fist order reaction the rate constant is 6.909 min^(-1) . The time taken for 75% conversion in minutes is :

Answer»

`(3)/(2) "LOG"2`
`(2)/(3)` log 3
`(2)/(3)` log 2
`(3)/(2)` log `(3)/(4)`

Solution :(C ) K = 6.909 `min^(-1)`
`t= (2.303)/(6.909)"log" (100)/(25)`
`=(2.303)/(6.909)xx"log" 4`
`= (2.303)/(6.909) xx2 "log" 2 = (2)/(3 ) "log" 2 `
13.

For a first reaction, t_(0.75) is 138.6 seconds. Its specific rate constant (in sec^(-1)) is

Answer»

`10^(-2)`
`10^(-4)`
`10^(-5)`
`10^(-6)`

Answer :C
14.

For a first reaction , show that time required for 99% completion is twice the time required for the completion of 90% of reaction.

Answer»

SOLUTION :For a FIRST REACTION, `t =k =(2.303)/t log.a/(a-x)`
99% completion means that
`x =99% ` of a = 0.99a
`:. t_(99%)=(2303)/k log. a/(a-0.99a)=(2.303)/klog 10^2=2xx(2303)/k`
90% completion means that
`x=90% " of " a = 0.90a`
`:. t_(99%)=(2303)/k log. a/(a-0.99a)=(2.303)/klog 10=2303/k`
`(t_(99%))/(t_(90%))=((2xx2303)/k)//(2.303)/k=2 " or " t_90%=2xxt_(90%)`
15.

For a first order reaction with rate constant k, which expression gives the half-life period ?

Answer»

`kln2`
`1//ka`
`0.639//k`
`3/(2ka^2)`

ANSWER :C
16.

For a first order reaction with rate constant 'k' and initial concentration 'a', the half-life period is given by

Answer»

`(ln2)/(k)`
`(1)/(KA)`
`(0.693)/(k)`
`(3)/(2ka^(2))`

Answer :A::C
17.

For a first order reaction with rate constant k and initial concentration a, the half-life period is given by

Answer»

In `3//k`
`1//ka`
`0.693//k`
`3//2ka^(2)`

ANSWER :C
18.

For a first order reaction with half-life of 150 seconds, the time taken for the, concentration of the reactant to fall from M/10 to M/100 will be approximately

Answer»

1500 s
500 s
900 s
600 s

Solution :`k = 0.693/(t_(1//2))= 0.693/150 s^(-1)= 2.303/t log. (1//10)/(1//100)`
`or t = (2.303xx 150)/(0.693) log 10 - 498 -=500S`
19.

For a first order reaction we have K=100s^(-1). The time for completion of 50% reaction is

Answer»

`10^(-2)s`
`4XX10^(-5)s`
`6.93xx10^(-3)s`
`7XX10^(-5)s`

ANSWER :C
20.

For a first order reaction with half life of 150 seconds, the time taken for the concentration of the reactant to fall from M/10 to M/100 will be approximately

Answer»

1500 s
500 s
900 s
600 s

Answer :B
21.

For a first order reaction velocity constant , K = 10^(-3) s^(-1) . Two third life for it would be

Answer»

1100 s
2200 s
3300 s
4400 s

Solution :We know that `k = (2.303)/(t)` log `(a)/(a-x)`
`10^(-3) = (2.303)/(t)` log `(a)/((a - (2a)/(3))) , 10^(-3) = (2.303)/(t)` log 3
`10^(-3) = (2.303)/(t) xx 0.4771 , t = (2.303 xx 0.4771)/(10^(-3))`
`= 1098.7` SEC = 1100 sec .
22.

For a first order reaction , to obtain a positive slope , we need to plot {where [A] is the concentration of reactant A}

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`- "log"_(10) [A]` VS t
`- "log"_(E) [A]` vs t
`log _(10) [A] vs ` log t
[A] vs t

Solution :For a FIRST order reaction to obtain a positive SLOPE , a graph is PLOTTED between `-"log"_(e)`[A] vs t.
23.

For a first order reaction, time taken for half of the reaction to complete is t_(1) whereas that for 3//4th of the reaction to complete is t_(2). How are t_(1) and t_(2) related to each other ?

Answer»

SOLUTION :`t_(2)=2t_(1).`This is because for `3//4th` of the reaction to COMPLETE, time required = two half-lives.
24.

For a first order reaction, time taken for half of the reaction to complete ist_(1)and 3/4 of the reaction to complete is t_(2). How are t_(1)and t_(2) related?

Answer»

Solution :`t_2=2t_1` because for 3/4th of the reaction to complete TIME REQUIRED is equal to TWO HALF LIVES.
25.

For a first order reaction , the time taken to reduce the initial concentrations by a factor of 1/4 is 20 minutes . The time required to reduce initial concentration by a factor of 1/16 is

Answer»

20 MIN
10 min
80 min
40 min

SOLUTION :`1 overset(1^(st))to1//2 overset(2^(nd))to1//4overset(3^(rd))to1//8 overset(4^(th))to1//16`
1/16 is 4 half-lives and 1/4 is 2 half-lives . It is given that the time taken for 2 half-lives is 20 MINUTES . So the time taken for 4 half-lives will be 40 minutes .
26.

For a first order reaction, the time taken to reduce the initial concentration by a factor of (1)/(4) is 20 minutes. The time required to reduce initial concentration by a factor of 1//16 is

Answer»

20 min
10 min
80 min
40 min

Solution :Time taken to REDUCE by factor of `(1)/(4) = 20` min.
`therefore` Time taken to reduce by factor of `(1)/(2)`
i.e., `t_(1//2) = 10 min`
`aoverset(t_(1//2))to(a)/(2)overset(t_(1//2))to(a)/(4)overset(t_(1//2))to(a)/(8)overset(t_(1//2))to(a)/(16)`
Toral time required ` = 4 xx t_(1//2) = 4 xx 10 min = 40 min`
27.

For a first order reaction, the time required for 99.9% of the reaction to take place is nearly

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10 TIMES that REQUIRED for HALF of the reaction
100 times that required for two-thirds of the reaction
10 times that required for one-fourth of the reaction
20 times that required for half of the reaction

Answer :A
28.

For a first order reaction the rate constant at 500 K " is " 8xx10^(-4)s^(-1) . Calculate the frequency factor , if the energy of activation for the reaction is 190"kJ mol"^(-1).

Answer»

Solution :`k= 8XX10^(-4) , T = 500 K E_a=190 " kJ MOL "^(-1)A = ? `
According to ARRHENIUS equation ,
`k=Ae^(-E_a//RT)`
ln k - ln a - `E_a/(RT)`
`logk=logA-E_a/(2.303RT)`
`logA=logk+(E_a)/(2.303RT)`
`log(8xx10^(-4))+(190)/(2.303xx8.314xx10^(-3)kJ //K^(-1)xx500)`
`logA=-3.096+190/(9573.57xx10^(-3))`
`logA=16.744`
A = Antilog (16.744)
`A = 5.546xx10^(16)s^(-1)`
29.

For a first- order reaction, the time required for 99.9%of the reaction to take place is nearly

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10 times that required for HALF the REACTION
100 times that required for two-third of the reaction
10 times that required for one- fourth of the reaction
20 times that required for half of the reaction .

ANSWER :A
30.

For a first order reaction, the rate constant is 6.909 "min"^(-1), the time taken for 75% conversion in minutes is

Answer»

`((3)/(2))log2`
`((2)/(3))log2`
`((3)/(2))LOG((3)/(4))`
`((2)/(3))log((4)/(3))`

SOLUTION :`k=((2.303)/(t))log(([A_(0)])/([A]))`
`[A_(0)]=100,[A]=25`
`6.909=((2.303)/(t))log((100)/(25))`
`t=((2.303)/(6.909))log(4)impliest=((1)/(3))log^(2)`
`t=((2)/(3))log^(2)`
31.

For a first order reaction , the rate constant is 6.909 "min"^(-1) . The time taken for 75% conversion in minutes is ........

Answer»

`(3/2)LOG2`
`(2/3)log2`
`(3/2)log(3/4)`
`(2/3)log(4/3)`

Solution :`k=((2.303)/t)log.(([A_0])/([A]))`
`[A_0]=100,[A]=25`
`6.909=((2.303)/t)log(100/25)`
`t=(2.303)/(6.909)log(4)impliest=(1/3)log2^2`
`t = (2/3)log2`
32.

For a first order reaction, the plot of log[A]_(t)vs t is linear with a

Answer»

POSITIVE SLOPE and ZERO intercept
positive slope and NON zero intercept
negative slope and zero intercept
negative slope and non zero intercept

Answer :A
33.

For a first order reaction, the half life is 50 sec. Identify the correct statement form the following.

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the reaction is almost COMPLET in 500 sec
the same QUANTITY of reactant is CONSUMED for every 50 sec of the reaction
quantity of reactant remaining after 100 sec is half of what remains after 50 sec
All the above three

Solution :`100overset(50"sec")(to)50 overset(50"sec")(to)25`
34.

For a first order reaction temperature coefficient is 2. If the value of K at 310K is 2 xx 10^(-2) "min''^(-1),t_(1//2) of reaction at 300K will be (in min)

Answer»

69.3
23.03
46.06
69.1

Answer :A
35.

For a first order reaction ,the half-life period is independent of…….

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INITIAL concentration
cuber ROOT of initial concentration
first POWER of FINAL concentration
square root of final concentration

Answer :D
36.

For a first order reaction, t_(av) (average life time), t_(50%) and t_(75%) are in the order :

Answer»

`t_(50)lt t_(av) lt t_(75),`
`t_(50)lt t_(75) lt t_(av),`
`t_(av)lt t_(50) lt t_(75),`
`t_(av)=t_(50) lt t_(75),`

Solution :`t_(av) = (1)/(k) = (1)/(0*693//t_(1//2)) = (t_(1//2))/(0*693)= 1*44 t_(50%)`
ALSO, we KNOW that `t_(75%) = 2 XX t_(50%)`
Hence, `t_(50%) lt t_(av) lt t_(75%)`
37.

For first order reaction t_(0.75) is 138.6 sec. Its specific rate constant is (ins^(-1))

Answer»

`10^(-2)`
`10^(-4)`
`10^(-5)`
`10^(-6)`

Answer :A
38.

For a first order reaction t_(0.75) is 1368 seconds, therefore, the specific rate constant in sec^(-1) is

Answer»

`10^(-3)`
`10^(-2)`
`10^(-9)`
`10^(-5)`

Solution :`k=(2.303)/(1386)"LOG"(100)/(100-75)` on solving we GET, `k=10^(-3)`
39.

For a first order reaction, show that the time required for 99% completion of a first order reaction is twice the time required for the completion of 90%.

Answer»

SOLUTION :For FIRST ORDER reaction, `t=(2.303)/(k)log""(a)/(a-x)`
`99%` completion means that `x=99%" of a=0.99" a"`
`t_(99%)=(2.303)/(k)log""(a)/(a-0.99a)=(2.303)/(k)log10^(2)=2XX(2.303)/(k)`
`90%` completion means that `x=90%" of "a=0.90" a"`
`:.""t_(90%)=(2.303)/(k)log""(a)/(a-0.99a)=(2.303)/(k)log10=(2.303)/(k)`
`:.""(t_(99%))/(t_(90%))=((2xx2.303)/(k))//((2.303)/(k))=2" or "t_(99%)=2xxt_(90%).`
40.

For a first order reaction, show thattime required for 99% completion is twice the time required for the completion of 90% of reaction.

Answer»

Solution :For first order REACTION, `t=(2.303)/(k)"log"(a)/(a-x)`
At 99% COMPLETION`x=99%` of a i.e., 0.99a
`therefore t(99%)=(2.303)/(k)"log"(a)/(a-0.99a)=(2.303)/(k) log 10^(2)= 2XX(2.303)/(k)`
At 90% completion MEANS that `x=90%` of a = 0.90 a
`therefore t(90%) =(2.303)/(k)"log"(1)/(a-0.90a)=(2.303)/(k)log 10=(2.303)/(k)`
`therefore (t(99%))/(t(90%))=((2xx2.303)/(k))//((2.303)/(k))=2.`
41.

For a first order reaction R rarrP, the rateconstantis k. if the initialconcentration of R is [R_(0)], theconcentration of R at any time't'is given by the expression-

Answer»

`[R_(0)]E^(KT)`
`[R_(0)](1-e^(-kt))`
`[R_(0)]e^(-kt)`
`[R_(0)](1-e^(kt))`

SOLUTION :N//A
42.

For a first order reaction, rate constant is 0.6932 "hr"^(-1) , then half-life for the reaction is

Answer»

`0.01` hr
1HR
2HR
10 hr

Solution :`t_(1//2) = (0.693)/(k)= (0.693)/(0.6932 hr^(-1)) = 1`hr .
43.

For a first-order reaction of the type nA to product where initial concentration of A is 'a' moles/litre. The correct expression for the rate constant or half-life is

Answer»

`k=2.303/(NT)"LOG"a/((a-x))`
`k=2.303/(t)"log"a/(a-x)`
`t_(1/2)=0.6932/k`
`t_(1/2)=0.6932/(NK)`

ANSWER :A::D
44.

For a first order reaction : R rarr P t_(1//2) is proportional to :

Answer»

`[A]^(1//2)`
`[A]^(0)`
[A]
`1//[A]`

ANSWER :B
45.

For a first order reaction, it takes 5 minutes for the initial concentration of 0.6" mol L"^(-1) to become 0.4" mol L"^(-1). How long in all will it take for the initial concentration to become 0.3" mol L"^(-1) ?

Answer»


SOLUTION :`a=0.6" MOL L"^(-1),(a-x)=0.4" mol L"^(-1),t=5" min",""K=(2.303)/(5" min")log""(0.6)/(0.4)=0.0811" min"^(-1),`
`0.6" mol L"^(-1)to0.3" mol L"^(-1)"means "t_(1//2).` Hence, `t_(1//2)=(0.693)/(0.0811" min"^(-1))=8.54" min".`
46.

For a first order reaction , nAtoB whose concentration vs time curve is as shown in the figure. If half -life for this reaction is 24 minutes. Find out the value of n .

Answer»

1
2
3
4

Solution :At t=48 min, [A]=[B]
Also, `[A]=([A]_0)/4=[B]`
`underset([A]_0-nx)(nA)toundersetx(B)`
`X=([A]_0)/4implies [A]_0-n([A]_0)/4=([A]_0)/4 implies n=3`
47.

For a first order reaction, it takes 16 min to complete 50% reaction. How much time does it take to complete 75% reaction?

Answer»

Solution :`K=0.693/t_(0.5)=0.693/16=0.0433min^-1`
Time required to COMPLETE` 75%`REACTION,
`t_(0.75)=2.303/K"log"100/(100-75)=2.303/0.0433"log"100/25=53.187xx0.06021=32`MINUTES.
48.

For a first order reaction involving decomposition of N_(2) O_(5) the following information is available : 2N_(2)O_(5)(g) rarr 4NO_(2) (g) +O_(2)(g) Rate =k [N_(2)O_(5)] N_(2)O_(5)(g) rarr 2NO_(2)(g) +1//2 O_(2) (g) Rate =k [N_(2)O_(5)) Which of the following expressions is true ?

Answer»

k=k
k=2k
k=1/2k
k `gt k`

Solution :(B) `2N_(2)O_(5)(G) rarr4NO_(2) +O_(2)(g) `
Rate = `=-(1)/(2)([N_(2)O_(5)])/(DT)=2k[N_(2)O_(5)]`
or Rate=` -(d[N_(2)O_(5)])/(dt)=2k[N_(2)O_(5)]`
For `N_(2)O_(5)rarr2NO_(2)+(1)/(2)O_(2)`
`-(d[N_(2)O_(5)])/(dt)=k[N_(2)O_(5)]`
or Rate `= - (d[N_(2)O_(5)])/(dt)= k[N_(2)O_(5)]`
Since rate must be same k = 2k
49.

For a first order reaction, if the time taken for completion of 50% of the reactionis t second, the time required for completion of 99.9% of the reaction is:

Answer»

10t
5t
100t
2t

Solution :`(Kxxt_(1))/(Kxxt_(2))=("LOG"100/50)/("log"100/0.1)impliest/(t_(2))=(log_(2))/(3log_(10)^(10)),t_(2)=(txx3)/0.3010=10xxt`
50.

For a first order reaction half life period t(1/2)is independent of initial concentration of its reacting species. By deriving the equation for t(1/2)of first order reaction, prove that t_(1/2)is independent of initial concentration of its reacting species.

Answer»

SOLUTION :For a FIRST order reaction,`k=2.303/tlog[[R_0]]/[[R]]`When t=`t_(1/2)[R]=[[R_0]]/2,`
`t_(1/2)=2.303/k LOG([[R_0]]/[[R_0]])/2 `
`2.303/klog2=(2.303xx0.3010)/k
thereforet^(1/2)=0.693/k`