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". |
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Answer» Rate of formation of `AB=2xx" Rate of disappearance of "B_(2)` |
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| 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? |
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Answer» <P>`x/m vs.p` |
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| 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. |
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Answer» 11.25 |
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| 4. |
Fora gas - solidadsorbentsystem, theadsorptionisotherm (x)/(m) = kp^(1//m) is applicable , where n=5in the specifiedcase . Select the correctstatement. |
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Answer» `(x)/(m)` vs p plotis a linear graph with slope EQUAL to 5. |
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| 5. |
For a gas reaction ArarrP at T (K) the rate is given by : Rate=k^(') p_(A)^(2) atm/hr |
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| 6. |
For a gas phasereaction , the unit of reaction rat is ....... |
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Answer» `s^(-1)` |
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| 7. |
For a gas (R//C_(v)) = 0.67, the gas is made up of molecules which are |
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Answer» Polyatomic |
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| 8. |
For a gas ((R)/(C_v)) = 0.67, the gas is made up of molecule which are : |
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Answer» Monoatomic |
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| 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. |
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Answer» `:. 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` |
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| 11. |
For a fixed amount of an ideal gas P us T plot is given as shown. Identify the correct option. |
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Answer» The change from A to B should be isochoric |
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| 12. |
For a fist order reaction the rate constant is 6.909 min^(-1) . The time taken for 75% conversion in minutes is : |
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Answer» `(3)/(2) "LOG"2` `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 ` |
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| 13. |
For a first reaction, t_(0.75) is 138.6 seconds. Its specific rate constant (in sec^(-1)) is |
| Answer» 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. |
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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%)` |
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| 15. |
For a first order reaction with rate constant k, which expression gives the half-life period ? |
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Answer» `kln2` |
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| 16. |
For a first order reaction with rate constant 'k' and initial concentration 'a', the half-life period is given by |
| Answer» Answer :A::C | |
| 17. |
For a first order reaction with rate constant k and initial concentration a, the half-life period is given by |
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Answer» In `3//k` |
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| 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 |
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Answer» 1500 s `or t = (2.303xx 150)/(0.693) log 10 - 498 -=500S` |
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| 19. |
For a first order reaction we have K=100s^(-1). The time for completion of 50% reaction is |
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Answer» `10^(-2)s` |
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| 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 |
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Answer» 1500 s |
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| 21. |
For a first order reaction velocity constant , K = 10^(-3) s^(-1) . Two third life for it would be |
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Answer» 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 . |
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| 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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Answer» `- "log"_(10) [A]` VS t |
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| 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 |
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Answer» 20 MIN 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 . |
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| 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 |
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Answer» 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` |
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| 27. |
For a first order reaction, the time required for 99.9% of the reaction to take place is nearly |
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Answer» 10 TIMES that REQUIRED for HALF of the reaction |
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| 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). |
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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)` |
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| 29. |
For a first- order reaction, the time required for 99.9%of the reaction to take place is nearly |
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Answer» 10 times that required for HALF the REACTION |
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| 30. |
For a first order reaction, the rate constant is 6.909 "min"^(-1), the time taken for 75% conversion in minutes is |
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Answer» `((3)/(2))log2` `[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)` |
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| 31. |
For a first order reaction , the rate constant is 6.909 "min"^(-1) . The time taken for 75% conversion in minutes is ........ |
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Answer» `(3/2)LOG2` `[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` |
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| 32. |
For a first order reaction, the plot of log[A]_(t)vs t is linear with a |
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Answer» POSITIVE SLOPE and ZERO intercept |
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| 33. |
For a first order reaction, the half life is 50 sec. Identify the correct statement form the following. |
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Answer» the reaction is almost COMPLET in 500 sec |
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| 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) |
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Answer» 69.3 |
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| 35. |
For a first order reaction ,the half-life period is independent of……. |
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Answer» INITIAL concentration |
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| 36. |
For a first order reaction, t_(av) (average life time), t_(50%) and t_(75%) are in the order : |
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Answer» `t_(50)lt t_(av) lt t_(75),` ALSO, we KNOW that `t_(75%) = 2 XX t_(50%)` Hence, `t_(50%) lt t_(av) lt t_(75%)` |
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| 37. |
For first order reaction t_(0.75) is 138.6 sec. Its specific rate constant is (ins^(-1)) |
| Answer» Answer :A | |
| 38. |
For a first order reaction t_(0.75) is 1368 seconds, therefore, the specific rate constant in sec^(-1) is |
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Answer» `10^(-3)` |
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| 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%. |
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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%).` |
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| 40. |
For a first order reaction, show thattime required for 99% completion is twice the time required for the completion of 90% of reaction. |
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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.` |
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| 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- |
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Answer» `[R_(0)]E^(KT)` |
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| 42. |
For a first order reaction, rate constant is 0.6932 "hr"^(-1) , then half-life for the reaction is |
| Answer» 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 |
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Answer» `k=2.303/(NT)"LOG"a/((a-x))` |
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| 44. |
For a first order reaction : R rarr P t_(1//2) is proportional to : |
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Answer» `[A]^(1//2)` |
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| 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) ? |
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Answer» `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".` |
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| 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 . |
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Answer» 1 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` |
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| 47. |
For a first order reaction, it takes 16 min to complete 50% reaction. How much time does it take to complete 75% reaction? |
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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. |
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| 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 ? |
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Answer» k=k 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 |
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| 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: |
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Answer» 10t |
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| 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. |
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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` |
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