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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 301. |
……..A….. Is the expression in which reaction rate is given in term of molar concentration of reactants with each term raised to some power, which may or may not be same as the stoichiometric coefficient of the reacting species in a balanced chemical equation. Here, A isA. Rate lawB. Rate equationC. Differential rate equationD. None of these |
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Answer» Correct Answer - A Rate law is the expression in which reaction rate is given in terms of molar concentration of reactants with each term raised to some power, which may or may not be same as the stoichiometric coefficient of the reacting species in a balanced chemical equation. |
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| 302. |
Give one example of pseudo first order reaction.A. inversion of cane sugarB. Decomposition of `H_(2)O_(2)`C. Conversion of cycopropane to propeneD. Decompostion of `N_(2)O_(5)` |
| Answer» Correct Answer - A | |
| 303. |
For a reaction `P+ Q to 2R +S ` which of the following statement is correct ?A. Rate of disappearance of P = Rate of appearance of SB. Rate of disappearance of `Q =2xx` Rate of appearance of RC. Rate of disppearance of P =Rate of appearance of QD. Rate of disapperance of `Q =(1)/(2) xx` rate of apperance of R |
| Answer» Correct Answer - B | |
| 304. |
Fill in the blanks by choosing the correct option . order of the reaction is the `underline (x)` of the powers to which concentration terms are raised in expermentally determined rate equation . The unit of first order rate constant is `underline (Y) ` the unit of first order rate constant when concentration is measured in terms of pressure and time in muutes is `underline(Z)`A. `X to " product ," Y to mol L^(-1) " time "^(-1) , Z to atm min^(-1)`B. `X to "sum " ,Y to mol ^(-1) , Z to atm min^(-1)`C. `x to " product " , Y to L mol ^(-1) ,Z to atm min^(-1)`D. `x to " sum " , Y to "time"^(-1),Zto min ^(-1)` |
| Answer» Correct Answer - D | |
| 305. |
Fill in the blanks by choosing the correct option. Order of the reaction is the `underline(X)` of the powers to which concentration terms are raised in experimentally determined rate equation. The unit of first order rate constant is `underline(Y)`. The unit of first order rate constant when concentration measured in terms of pressure and time in minutes is `underline(Z)`A. `X to` product, `Y to mol L^(-1) "time"^(-1), Z to "atm" "min"^(-1)`B. `X to` sum `Y to L mol^(-1) "time"^(-1), Z to "atm" "min"^(-1)`C. `X to` product, `Y to L mol^(-1), Z to "atm" "min"^(-1)`D. `X to` sum, `Y to "tim"^(-1), Z to "min"^(-1)` |
| Answer» Correct Answer - D | |
| 306. |
The sum of powers to which of the concentration terms are raised in the rate law is called molecularity of the reaction. |
| Answer» Correct Answer - F | |
| 307. |
What is the activation energy for the decomposition of `N_(2)O_(5)` as `N_(2)O_(5) hArr 2NO_(2)+1/2 O_(2)` If the values of the rate constants are `3.45 xx 10^(-5)` and `6.9 xx 10^(-3)` at `27^(@)C` and `67^(@)C` respectivelyA. `102 xx 10^(2) kJ`B. `488.5 kJ`C. `112 kJ`D. `14.7 kJ` |
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Answer» Correct Answer - D `"log"(6.9 xx 10^(-3))/(3.45 xx 10^(-3)) = (E_(a)(340 - 300))/(8.314 xx 10^(-3) xx 2.303 xx 300 xx 340)` `:. E_(a) = (0.301 xx 8.314 xx 10^(-3) xx 2.303 xx 300 xx 340)/(40)` `= 14.7 KJ` |
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| 308. |
For the decomposition reaction: `N_(2)O_(4(g))rarr 2NO_(2(g))`, the initial pressure of `N_(2)O_(4)` falls from `0.46` atm to `0.28` atm in `30` minute. What is the rate of appearance of `NO_(2)`? |
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Answer» Rate of reaction `=-(d[N_(2)O_(4)])/(dt)=1/2(d[NO_(2)])/(dt)` `:. 1/2(d[NO_(2)])/(dt)=-((0.28-0.46))/(30)` `:. 1/2(d[NO_(2)])/(dt)=6xx10^(-3)` `(d[NO_(2)])/(dt)=1.2xx10^(-2) atm min^(-1)` |
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| 309. |
The initial concentration of `N_(2)O_(5)` in the following first order reaction: `N_(2)O_(5)(g) rarr 2NO_(2)(g)+(1)/(2)O_(2)(g)` was `1.24 xx 10^(-2) mol L^(-1)` at `318 K`. The concentration of `N_(2)O_(5)` after `60 min` was `0.20 xx 10^(-2) mol L^(-1)`. Calculate the rate constant of the reaction at `318 K`. |
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Answer» For the first order reaction, `k=2.303/t log a/(a-x)` a=`1.24 xx 10^(-2) mol L^(-1), (a-x) = 0.20 xx 10^(-2) mol L^(-1)`, t=60 min `k=2.303/(60min) xx log(1.24 xx 10^(-2) mol L^(-1))/(0.20 xx 10^(-2) mol L^(-1))= 2.303/(60 min)log6.2` `=2.303/(60 min) xx 0.7924 = 0.0304 min^(-1)` |
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| 310. |
A reaction that is of the first order with respect to reactant A has a rate constant `6 "min"^(-1)`. If we start with `[A] = 0.5 "mol" 1^(-1)`, when would `[A]` reach the value `0.05 mol 1^(-1)`A. 0.384 minB. 0.15 minC. 3 minD. 3.84 min |
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Answer» Correct Answer - a We know that for first order kinetics `k = (2.303)/(t)` log `(a)/(a-x)` `(a-x) = 0.05` mol `l^(-1) , 6 = (2.303)/(t)` log `(0.5)/(0.05)` or `t = (2.303)/(6)` log `(0.5)/(0.05) = (2.303)/(6) = 0.384` min . |
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| 311. |
The rate constant of a reaction with respect to the reactant A is `6 min^(-1)`. If we start with [A] = `0.8 mol L^(-1)`, when would [A] reach the value of `0.08 mol^(-1)`? |
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Answer» For the first order reaction, `t=2.303/k log a/(a-x)` `a=0.8 mol L^(-1),(a-x)=0.008 mol L^(-1), k=6min^(-1)` `t = (2.303)/(6min^(-1)) log (0.8 mol L^(-1))/(0.08 mol L^(-1)) = 2.303 / (6 min^(-1)) log 10 = 0.38 min` |
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| 312. |
An elementary reaction is given as `2P + Q rarr` products. If concentration of `Q` is kept constant and concentration of `P` is doubled then rate of reaction isA. doubledB. halvedC. quadrupledD. remains same |
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Answer» Correct Answer - C `r = K[P]^(2)[Q]` `r_(1) = K[2P]^(2)[Q]` `:. (r_(1))/(r ) = 4 rArr r_(1) = 4r` |
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| 313. |
For a reaction A+B `to` Products, the rate law is -Rate = `k[A][B]^(3//2)` Can the reaction be an elementary reaction? Explain. |
| Answer» In an elementary reaction, the number of atoms or ions which are colliding to react is known as molecularity. Had the reaction been of elementary nature (single step reaction) the order of reaction with respect should have been 1 but it is `3//2` i.e. fractional. This shows that the reactioin is of complex nature and is not elementary reaction. | |
| 314. |
For a certain reaction a large fraction of molecules has energy more than the threshold energy, still the rate of reaction is very slow. The possible reason for this could be thatA. the colliding molecules could be large in sizeB. the colliding molecules must not be properly oriented for effective collisionsC. the rate of reaction could be independent of the energyD. one of the reactant cound be in excess. |
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Answer» Correct Answer - B Apart from energy considerations the colliding molecules should have proper orientation for effective collisions. |
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| 315. |
Chemical reactions with very high `E_(a)` values are generallyA. Very fastB. Very slowC. Moderately fastD. Spontaneous |
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Answer» Correct Answer - b If the activation energy for a reaction is low , the fraction of effective collisions will be large and the reaction will be fast . On the other hand , if the activation energy is high , then fraction of effective collisions will be small and the reaction will be slow . |
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| 316. |
During decomposition of an activated complexA. energy is always releasedB. energy is always absorbedC. energy does not changeD. reactants may be formed |
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Answer» Correct Answer - A::D |
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| 317. |
For a reaction , activation energy `(E_(a) ) = 0` and rate constant `(K) = 3.2 xx 10^(6) s^(-1)` at 300 K . What is the value of the rate constant at 310 KA. `3.2 xx 10^(-12) s^(-1)`B. `3.2 xx 10^(6) s^(-1)`C. `6.4 xx 10^(12) s^(-1)`D. `6.4 xx 10^(6) s^(-1)` |
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Answer» Correct Answer - b When `E_(a) = 0` rate constant is independent of temperature . |
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| 318. |
Which graph shows zero activation energy ?A. B. C. D. |
| Answer» Correct Answer - C | |
| 319. |
The activation energy of a reaction is zero. The rate constant of the reactionA. increases with increaes in temperatureB. decreases with increases in temperatureC. increases with decrease in temperatureD. is almost independent of temperature |
| Answer» Correct Answer - D | |
| 320. |
Which increases on increase of temperatureA. Energy of activation ` (E_(a))`B. Collision frequency (Z)C. Rate constant (k)D. Both (b) and ( c) |
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Answer» Correct Answer - d The collisions frequency (Z) and rate constant (k) increase on increase of temperature . With the increase in temperature , the average kinetic energy of the molecules increases and this leads to an increase in number of collisions per unit time (Z). The rate constant (k) of a reaction is also increases with increase of temperature . |
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| 321. |
Which of the following statements is/are correct?A. The rate of the reaction involving the converison of ortho-hydrogen to parahydrogen is `-(d[H_(2)])/(dt) = k[H_(2)]^(3//2)`.B. The rate of the reaction involving the thermal decompoistion of acetaldehyde is `k[CH_(3)CHO]^(3//2)`.C. In the formation of phosgene gas form `CO` and `Cl`, the rate of the reaction is `k[CO][Cl_(2)]^(1//2)`.D. In the decompoistion of `H_(2)O`, the rate of the reaction is `k[H_(2)O_(2)]`. |
| Answer» Correct Answer - A::B::C::D | |
| 322. |
Why do most chemical reaction rates increases rapidly as the temperature risesA. The fraction of molecules with kinetic energy greater than the activation energy increases rapidly with temperatureB. The average kinetic energy increases as temperature risesC. The activation energy decreases as temperature risesD. More collisions take place between particles so that the reaction can occur |
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Answer» Correct Answer - a As the temperature rises , the molecules gain more kinetic energy and more number of collisions takes place leading to speeding up of reaction i.e., increasing the rate of reaction . |
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| 323. |
The rate of a chemical reaction generally increases rapidly even for small temperature rise because of rapid increases in theA. Colliison frequencyB. Activation energyC. Fraction of molecules with energies in exess of the activation energyD. Avergae kinetic energy of the molecules |
| Answer» Correct Answer - C | |
| 324. |
The rate of a chemical reaction generally increases rapidly even for small temperature increases because of a rapid increase inA. Colliison frequencyB. Fraction of molecules with energies in excess of the activation energyC. Activation energyD. Average kinetic energy of molecules |
| Answer» Correct Answer - B | |
| 325. |
Why coal or petrol does not burn by itself in air but once initiated by flame, it continues to burn? |
| Answer» The activation energy needed for the combustion of coal i.e. the oxidation of carbon is very high and is not available at room temperature. When brought in contact with the flame, a part of the coal in its contact absorbs heat as activationi energy. Since combusion is an exothermic reaction, the heat energy which is liberated further provides activation energy for the combusion to continue. | |
| 326. |
A first order reaction has a rate constant `1.15xx10^(-3)s^(-1)`. How long will `5g` of this reactant take to reduce to `3g`` ? |
| Answer» Correct Answer - t=444 s | |
| 327. |
In a first-order reaction `A rarr B`, if `K` is the rate constant and initial concentration of the reactant is `0.5 M`, then half-life isA. `(log2)/(k)`B. `(log2)/(ksqrt(0.5))`C. `(ln2)/(k)`D. `(0.693)/(0.5k)` |
| Answer» Correct Answer - C | |
| 328. |
The rate constants of a reaction at 500 K and 700 K are `0.02s^(-1)` and `0.07s^(-1)` respectively. Calculate the values of `E_(a)` and A. |
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Answer» According to Arrhenius equation, `logk_(2)/k_(1)= E_(a)/(2.303R)[(T_(2)-T_(1))]/(T_(1)T_(2))` `k_(1)= 0.02s^(-1),k_(2)=0.07s^(-1), T_(1)= 500K, T_(2)= 700K` `log 0.07/0.02 = (E_(a))/((2.303 xx 8.314 JK^(-1)mol^(-1)))[(700K-500K)/(700K xx 500K)]` `log 3.5 = (E_(a))/(2.303 xx 8.314 JK^(-1)mol^(-1))xx((200K)/(700K xx 500K))` `E_(a) = (0.5441 xx 2.303 xx 8.314 xx 700 xx 500)/(200) J mol^(-1)= 18231.4 J mol^(-1)= 18.23 kJmol^(-1)` log k = `(-E_(a))/(2.303R) + log A or log A=log K + (E_(a))/(2.303RT)` log A `= log 0.02 + (18231.4 J mol^(-1))/(2.303 xx 8.314JKmol^(-1) xx 500K)` `=-log 50 + 1.904 = -1.699 + 1.904 = 0.205` A= Antilog 0.205 = 1.603 |
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| 329. |
The rate constant of a reaction at `500 K` and `700 K` are `0.02s^(-1)`, respectively. Calculate the values of `E_(a)` and `A` at `500 K`. |
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Answer» `logk_(2)/k_(1)=E_(a)/(2.323R)[(T_(2)-T_(1))/(T_(1)T_(2))]` `"log"k_(2)/k_(1)=(E_(a)/(2.323xx8.314JK^(-1)"mol"^(-1)))[(700-500)/(700xx500)]` `0.544= E_(a)xx 5.714xx10^(-4)//10.15` `E_(a)=xx 0.544xx19.15//5.714xx10^(-4)=18230.8J` Since ` k=Ae^(-Ea//RT` `0.02=Ae^(-18230.8//8.314xx500` `A= 0.02//0.02=1.61` |
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| 330. |
For the chemical reaction `I^(ɵ) + OCl^(ɵ) rarr Cl^(ɵ) + OI^(ɵ)` Rate `= (k[OCl^(ɵ)] [I^(ɵ)])/([overset(ɵ)(OH)]` a. What is the order and moleculartiy of the reaction ? b. In the above reaction, what are the molecularity and order with respect toA. `1,2`B. `2,1`C. `2,2`D. `3,2` |
| Answer» Correct Answer - A | |
| 331. |
Write the rate rate equatioin for the reaction `2A + B to C` if the order of the reaction is zero. |
| Answer» Rate = `k[A]^(0)[B]^(0)= k` | |
| 332. |
A colliison between reactant molecules must occur with a certain minimum energy before it is effective in yielding Product molecules. This minimum energy is called activation energy `E_(a)` Large the value of activation energy, smaller the value of rate constant `k`. Larger is the value of activation energy, greater is the effect of temperature rise on rate constant `k`. `E_(f) =` Activation energy of forward reaction `E_(b) =` Activation energy of backward reaction `Delta H = E_(f) - E_(b)` `E_(f) =` threshold energy The activation eneries for forward and backward reactions in a chemical reaction are `30.5` and `45.4 kJ mol^(-1)` respectively. The reaction isA. exothermicB. endothermicC. neithter exothermic nor endothermicD. idenpendent of temperature |
| Answer» Correct Answer - A | |
| 333. |
A colliison between reactant molecules must occur with a certain minimum energy before it is effective in yielding Product molecules. This minimum energy is called activation energy `E_(a)` Large the value of activation energy, smaller the value of rate constant `k`. Larger is the value of activation energy, greater is the effect of temperature rise on rate constant `k`. `E_(f) =` Activation energy of forward reaction `E_(b) =` Activation energy of backward reaction `Delta H = E_(f) - E_(b)` `E_(f) =` threshold energy For two reactions, activation energies are `E_(a1)` and `E_(a2)`, rate constant are `k_(1)` and `k_(2)` at the same temperature. If `k_(1) gt k_(2)`, thenA. `E_(a_(1))gtE_(a_(2))`B. `E_(a_(1))=E_(a_(2))`C. `E_(a_(1))ltE_(a_(2))`D. `E_(a_(1))geE_(a_(2))` |
| Answer» Correct Answer - C | |
| 334. |
A colliison between reactant molecules must occur with a certain minimum energy before it is effective in yielding Product molecules. This minimum energy is called activation energy `E_(a)` Large the value of activation energy, smaller the value of rate constant `k`. Larger is the value of activation energy, greater is the effect of temperature rise on rate constant `k`. `E_(f) =` Activation energy of forward reaction `E_(b) =` Activation energy of backward reaction `Delta H = E_(f) - E_(b)` `E_(f) =` threshold energy The rate constant of a certain reaction is given by `k = Ae^(-E_(a)//RT)` (where `A =` Arrhenius constant). Which factor should be lowered so that the rate of reaction may increase?A. TB. ZC. AD. `E_(a)` |
| Answer» Correct Answer - D | |
| 335. |
A colliison between reactant molecules must occur with a certain minimum energy before it is effective in yielding Product molecules. This minimum energy is called activation energy `E_(a)` Large the value of activation energy, smaller the value of rate constant `k`. Larger is the value of activation energy, greater is the effect of temperature rise on rate constant `k`. `E_(f) =` Activation energy of forward reaction `E_(b) =` Activation energy of backward reaction `Delta H = E_(f) - E_(b)` `E_(f) =` threshold energy In a hypothetical reaction `A rarr B`, the activation energies for the forward and backward reactions are `15` and `9 kJ mol^(-1)`, respectively. The potential energy of `A` is `10 kJ mol^(-1)`. Which of the following is wrong?A. Threshold energy or the reaction is 25 kJB. The potential energy of B is 16 kJC. Heat of reaction is 6 kJD. The reaction is exothermic |
| Answer» Correct Answer - D | |
| 336. |
Assertion : Order of a reaction with respect to any reactant can be zero, positive negative of fractional. Reason : Rate of a reaction cannot decrease with increase in concentration of a reactant or a product.A. If both assertion and reason are true and reason is the correct explanation of assertion.B. If both assertion and reason are true but reason is not the correct explanation of assertion.C. If assertion is true but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - C Rate of a reaction increases with increases in concentration of reactants and also depends on the order of reaction. |
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| 337. |
The rate of certain hypothetical reaction `A+B+C rarr` Products, is given by `r = -(dA)/(dt) = k[A]^(1//2)[B]^(1//3)[C]^(1//4)` The order of a reaction is given byA. 1B. 2C. 1/2D. 5/4 |
| Answer» Correct Answer - D | |
| 338. |
A colliison between reactant molecules must occur with a certain minimum energy before it is effective in yielding Product molecules. This minimum energy is called activation energy `E_(a)` Large the value of activation energy, smaller the value of rate constant `k`. Larger is the value of activation energy, greater is the effect of temperature rise on rate constant `k`. `E_(f) =` Activation energy of forward reaction `E_(b) =` Activation energy of backward reaction `Delta H = E_(f) - E_(b)` `E_(f) =` threshold energy If a reaction `A + B rarr C` is exothermic to the extent `30 kJ mol^(-1)` and the forward reaction has an activation energy of `249 kJ mol^(-1)` the activation energy for reverse reaction in `kJ mol^(-1)` isA. 324B. 279C. 40D. 100 |
| Answer» Correct Answer - D | |
| 339. |
Assertion (A) : An order with respect to any reactant or Product can be zero, poistive, negative, and fractional. Reason (R ): Rate cannot decrease with increase in the concentration of a reactant or Product.A. If both (A) and (R) are correct but (R) is the correct explanation of (A) .B. If both (A) and (R) are correct but (R) is not the correct exaplanation of (A)C. If (A) is correct but (R) is incorrectD. If (A) is incorrect but (R) is correct |
| Answer» Correct Answer - C | |
| 340. |
A zero order reactio is one:A. in which reactant is one:B. in which one of the reactant is in large excessC. whose rate is uniform and not affected by timeD. whose rate increases with time |
| Answer» Correct Answer - D | |
| 341. |
Assertion : The hydrolysis of methyl acetate by dil. HCl is a pseudo first order reaction Reason : HCl acts as a catalyst for the hydrolysis .A. If both assertion and reason are true and the reason is the correct explanation of the assertion .B. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false . |
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Answer» Correct Answer - b The correct reason is that during hydrolysis water is taken in large excess , therefore its concentration does not change during hydrolysis . |
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| 342. |
Assertion : Molecularity has no meaning for a complex reaction . Reason : The overall molecularity of a complex reaction is equal to the molecularity of the slowest step .A. If both assertion and reason are true and the reason is the correct explanation of the assertion .B. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false . |
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Answer» Correct Answer - b Molecularity of a reaction can be defined only for an elementary reaction because complex reaction does not take place in one single step and it is almost impossible for all the total molecules of the reactants to be in a state of encounter simultaneously . |
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| 343. |
Assertion : The order of a reaction can have fractional value . Reason : The order of a reaction cannot be written from balanced equation of a reactionA. If both assertion and reason are true and the reason is the correct explanation of the assertion .B. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false . |
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Answer» Correct Answer - b It is an experimentally determined value and depends upon the concentration change of reactant . It changes with pressure , temperature and concentration and it can have the fractional value . |
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| 344. |
Assertion (A) : The order of a reaction can have fractional value Reason (R) : The order of a reaction cannot be written from balanced equation of a reaction.A. If both (A) and (R) are correct but (R) is the correct explanation of (A) .B. If both (A) and (R) are correct but (R) is not the correct exaplanation of (A)C. If (A) is correct but (R) is incorrectD. If (A) is incorrect but (R) is correct |
| Answer» Correct Answer - B | |
| 345. |
For a second order reaction `dx//dt =k(a-x)^(2)`. Its half life periof isA. `(1)/(a.k)`B. `(0.693)/(k)`C. `(a)/(k)`D. `(0.693)/(ak)` |
| Answer» Correct Answer - A | |
| 346. |
Assertion: Order of the reaction can be zero or fractional. Reason: We cannot determine order from balanced chemical equation.A. Both assertion and reason are correct and the reason is correct explanation of assertion.B. Both assertion and reason are correct but reason does not explain assertion.C. Assertion is correct but reason is incorrectD. Both assertion and reason are incorrect. |
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Answer» Correct Answer - B |
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| 347. |
The inverison of a sugar follows first order rate equation which can be followed by noting the change in the rotation of the plane of polarization of light in the polarimeter. If `r_(oo), r_(f)` and `r_(0)` are the rotations at `t = oo, t = t`, and `t = 0`, then the first order reaction can be written asA. `k = (1)/(t)log.(r_(1)-r_(oo))/(r_(o) -r_(oo))`B. `k = (1)/(t)ln.(r_(0)-r_(oo))/(r_(t)-r_(o))`C. `k = (1)/(t)ln.(r_(oo)-r_(o))/(r_(oo)-r_(t))`D. `k = (1)/(t)ln.(r_(oo)-r_(t))/(r_(oo)-r_(0))` |
| Answer» Correct Answer - B | |
| 348. |
The inverison of cane sugar is a……………reaction though its molecularity is………………. . |
| Answer» Correct Answer - one, two | |
| 349. |
Decompoistion of hydrogen peroxide, `2H_(2)O_(2) rarr 2H_(2)O + O_(2)` is a …………. . |
| Answer» Correct Answer - first order | |
| 350. |
Assertion: Temperature coefficients of most of the reactions lies between `2` and `3`. Reason: Increases in temperature increases the number of collisions.A. If both assertion and reason are true and the reason is the correct explanation of the assertion.B. If both assertion and reason are true but the reason is not the correct explanation of the assertion.C. If assertion is true but reason is false.D. If assertion is false but reason is true. |
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Answer» Correct Answer - B Correct explanation. With increase of temperature by `10^(@)`, the fraction of molecules having effective collisions becomes `2` or `3` times. |
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