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All questions of Rates of Chemical Reaction for JAMB Exam

For a reaction,
 
hen x, y and z are 
  • a)
    1:1:1
  • b)
    3:2:3
  • c)
    3:3:2
  • d)
    2:2:3
Correct answer is option 'C'. Can you explain this answer?

Divey Sethi answered
For the reaction: xA + yB → zC

Given that,

Multiplying equation 2 by 1/3, we get

On comparing equation 1 and 3,
x = 3, y = 3, z = 2.

For a chemical reaction the rate constant is nearly doubled with the rise in temperature by
a)100ºC
b)10ºC
c)50ºC
d)273ºC
Correct answer is option 'B'. Can you explain this answer?

Rohit Shah answered
It has been found that rate constant is nearly doubled for a chemical reaction with a rise in temperature by 10deg. We can explain the dependence of the rate of a chemical reaction on temperature by Arrhenius equation.

 For the reaction  . The variation of the concentration of the products is given by curve
 
  • a)
    Y
  • b)
    W
  • c)
    Z
  • d)
    X
Correct answer is option 'A'. Can you explain this answer?

Divey Sethi answered
For the reaction, A+B⟶C+D, the  variation of the concentration of the products is given by the curve Y.
Initially, the product concentration is 0, then it gradually rises and reaches a maximum value. After that it remains constant. 
This behavior is represented by the curve Y.
Payal Sapra answered
Hi tausif. ...let dr/dt is proportional to [A]^n is equation 1st.... then 1/2 dr/dt is prportional to [2A]^n.....equation 2nd compare both equations...u'll get 2^n is equal to 1/2....so we get n is equal to minus 1..... hope u get it

The effect of temperature on reaction rate is given by
  • a)
    Arrhenius equation
  • b)
    Kirchoff’s Equation
  • c)
    Clauius Claperyron equation
  • d)
    Gibb’s Helmholtz equation
Correct answer is option 'A'. Can you explain this answer?

T.ttttt answered
Increasing the temperature increasesreaction rates because of the disproportionately large increase in the number of high energy collisions. It is only these collisions (possessing at least the activation energy for the reaction) which result in a reaction.

 A foreign substance that increase the speed of a chemical reaction is called
  • a)
    promotor
  • b)
    catalyst
  • c)
    moderator
  • d)
    inhibitor
Correct answer is option 'B'. Can you explain this answer?

Nandini Patel answered
Catalyst: Substances which alter  the rate of a chemical reaction and themselves remain chemically and quantitatively unchanged  after the reaction are known as catalysts and the phenomenon is known as catalysis.

Direction (Q. Nos. 1-13) This section contains multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONLY ONE is correct
Q. In the following reaction, which has maximum rate w.r.t. rate of disappearance of NH3?
4NH3 + 50  4NO + 6H2O
  • a)
    O2
  • b)
    NO
  • c)
    H2O
  • d)
    Equal
Correct answer is option 'C'. Can you explain this answer?

Nabanita Basu answered
Understanding the Reaction
The given reaction is:
4NH3 + 5O2 → 4NO + 6H2O
This reaction involves the disappearance of ammonia (NH3) and the appearance of the products NO and H2O.
Rate of Reaction
The rate of a chemical reaction can be expressed in terms of the rate of disappearance of reactants or the rate of appearance of products.
Stoichiometry of the Reaction
- According to the stoichiometry:
- 4 moles of NH3 produce 4 moles of NO and 6 moles of H2O.
- The coefficients in the balanced equation indicate the relative rates of disappearance and appearance.
Rate of Disappearance
- The rate of disappearance of NH3 is given by:
Rate = - (1/4) * d[NH3]/dt
- The rates for O2, NO, and H2O can be expressed similarly:
- O2: Rate = - (1/5) * d[O2]/dt
- NO: Rate = (1/4) * d[NO]/dt
- H2O: Rate = (1/6) * d[H2O]/dt
Comparison of Rates
To find the maximum rate of disappearance, we can compare the rates derived from the balanced equation:
- NH3: - (1/4) (for every 1 mole of disappearance)
- O2: - (1/5) (for every 1 mole of disappearance)
- NO: (1/4) (for every 1 mole of appearance)
- H2O: (1/6) (for every 1 mole of appearance)
The fractions reveal how many moles of each substance are involved in the reaction. The lower the denominator, the higher the rate of disappearance or appearance.
Conclusion
- Among the reactants and products, H2O has the highest coefficient when considering the rate of disappearance of NH3.
- Therefore, the maximum rate of disappearance is related to H2O's formation.
Thus, the correct answer is option 'C' (H2O).

Reaction kinetics deals with the study of
  • a)
    Rate of reaction
  • b)
    Mechanism of reaction
  • c)
    Factors which affects the rate of reaction
  • d)
    All of the mentioned
Correct answer is option 'D'. Can you explain this answer?

Om Desai answered
Reaction kinetics deals with the study of rate of reaction, their mechanism and the factors which affects the rate of reaction. It specifies all the general characteristics of a chemical reaction.

. What will be the value of instantaneous rate of reaction from the graph?
16578_eq2(10)
  • a)
    rinst = 1/ Slope
  • b)
    rinst = Slope
  • c)
    rinst = – Slope
  • d)
    rinst = – 1/ Slope
Correct answer is option 'B'. Can you explain this answer?

Preeti Iyer answered
If you make a graph of concentration of reactant vs time, the instantaneous reaction rate at a given time is the slope of the tangent line at that point in time. It is also the value of the rate law at a specific concentration (dA/dt is rate = k [A]).

The rate equation for the reaction,
2A + B → C
is found to be, rate = k[A] [B]
Q. The correct statement in relation to this reaction is that the
  • a)
    unit of k must be s-1
  • b)
    t1/2 is constant
  • c)
    rate of formation of C is half of the rate of disappearance of A
  • d)
    value of k is independent of the initial concentration of A and 8
Correct answer is option 'C'. Can you explain this answer?

Amar Jain answered
Rate = k (A)[B]
The given reaction is first order in A and first order is B.
Thus, total order = 2
(a) Unit of k = cone 1 - n time -1 = conc-1 time-1 Thus, (a) is false.
(b)  of second-order reaction, thus (b) is false. 
Thus, (c) is correct.

Thus, value of k is dependent on the concentration of A and B. Thus, (d) is false.

For the reaction,
Thus,
  • a)
    k1 = k2 = k3
  • b)
    2k1 = k2 = 4k3
  • c)
    2k1 = 4k2 = k3
  • d)
    None of these
Correct answer is option 'B'. Can you explain this answer?

Chetu Bola answered
V hav a formula. I. E For a reaction aA-----bB+cC Rate of reaction is [A] /[t]. a AC to given, 1/2[N205]/[t]=k1[N205]/2------eq(1) 1/4[N02]/[t]=k2[N205]/4------eq(2) 1/1[02]/[t]=k3[02]------eq(3) On diving all d 3 equations, v get K1/2=k2/4=k3 Multiply vit 4 to all d ratios V get 2k1=k2=4k3

Direction (Q. No. 14) Choices for the correct combination of elements from Column I and Column II are given as options (a), (b), (c) and (d), out of which one is correct.
  • a)
    a
  • b)
    b
  • c)
    c
  • d)
    d
Correct answer is option 'C'. Can you explain this answer?

Harsh Singhal answered
For 2nd graph half live is cons.on increasing conc.so it is of 1st order
for 1st graph rate remains cons.with time means independent on conc.so it is of 0 order
so ans.is c

Identify the incorrect statement
  • a)
    ftp stands for file transfer protocol
  • b)
    ftp uses two parallel TCP connections
  • c)
    ftp sends its control information in band
  • d)
    ftp sends exactly one file over the data connection
Correct answer is option 'C'. Can you explain this answer?

Hansa Sharma answered
Out-of-band controlis a characteristic of network protocols with which data control is regulated. Out-of-band control passes control data on a separate connection from main data. Protocols such asFTPuse out-of-band control. FTP uses two parallel TCP connections, one connection for sending control information (such as a request to transfer a file) and another connection foractually transferring the file. Because the control information is not sent over the same connection that the file is sent over, FTP sends control information out of band

Chemical substances speeding up the rate of chemical reaction is called as
  • a)
    pressure
  • b)
    concentration
  • c)
    catalysts
  • d)
    inhibitors
Correct answer is option 'C'. Can you explain this answer?

Preeti Iyer answered
A catalyst is a substance that speeds up the rate of the reaction without being consumed by the reaction itself. When a catalyst is added, the activation energy is lowered because the catalyst provides a new reaction pathway with lower activation energy.

Passage III
A reaction between substances A and B is represented as:
Observations on the rate of this reaction are obtained as :
Q.
Rate constant of the overall reaction is
  • a)
    5.0 * 10-2 M-1 h-1
  • b)
    5.0 * 10-2  M-2 h-1 
  • c)
    5.0 * 10-2 h-1
  • d)
    5.0 * 10-2 mh-1
Correct answer is option 'B'. Can you explain this answer?

Gunjan Lakhani answered

where, a == order w.r.t. A, 6 = order w.r.t. B
(i) 5.0 x 10-3 = K [0.1]a [1.0]b
(ii) 2.0 x 10-2 = k [ 0.1]a[2.0]b
(iii) 2.5 x 10-3 = k [0.05]a[1.0]b
From Eqs. (i) and (ii), we get
(2)2 = (2)b
∴ b = 2
Order w.r.t.B = 2
From Eqs. (i) and (iii), we get
(2) = (2)a
a = 1
Order w.r.t.A 
From Eq. (ii), 
5.0 x 10-3 = k (0.1) (1.0)2
∴ k = 5.0 x 10-2m-2h-1

Kinetics of the following reaction,
can be studied by
  • a)
    measurement of pH
  • b)
    titration with hypo after adding Kl
  • c)
    titration with AgNO3 solution
  • d)
    All of the above
Correct answer is option 'B'. Can you explain this answer?

Aditya Sen answered
Cl-atom attached to N-atom, is an oxidising agent and can oxidise Kl to l2.

l2 can be titrated using hypo in iodometric titration.

Cl-atom attached to benzene nucleus is not an oxidising agent.

Rate law cannot be determined from balanced chemical equation if _______.
  • a)
    reverse reaction is involved.
  • b)
     it is an elementary reaction.
  • c)
     it is a sequence of elementary reactions.
  • d)
    any of the reactants is in excess.
Correct answer is option 'A,C,D'. Can you explain this answer?

Geetika Shah answered
A catalyst is a substance that speeds up the rate of the reaction without being consumed by the reaction itself. When a catalyst is added, the activation energy is lowered because the catalyst provides a new reaction pathway with lower activation energy.

The decomposition of NO2 at 400 K proceeds at a of rate of 5.4 x 10 -5 mol L-1 s-1 when [NO2] = 0.01 mol-1
2 NO2(g) → 2NO(g ) + O2(g).
Q. Rate constant of the reaction will be 
  • a)
    0.54 L mol-1 s-1
  • b)
    0.54 x 10-3 L mol-1 s-1
  • c)
    5.4 s-1
  • d)
    0.54s-1
Correct answer is option 'A'. Can you explain this answer?

Simran Patel answered
Understanding the Reaction Rate
The given reaction is:
2 NO2(g) → 2 NO(g) + O2(g)
The rate of the reaction is expressed as:
Rate = - (1/2) d[NO2]/dt
Given:
- Rate = 5.4 x 10^-5 mol L^-1 s^-1
- [NO2] = 0.01 mol L^-1
Rate Law Expression
For this reaction, the rate law can be expressed as:
Rate = k [NO2]^n
Where:
- k = rate constant
- n = order of the reaction
Assuming the reaction is first-order with respect to NO2 (n = 1):
Calculating the Rate Constant (k)
1. Substitute the given values into the rate law:
- Rate = k [NO2]
- 5.4 x 10^-5 mol L^-1 s^-1 = k (0.01 mol L^-1)
2. Rearranging the equation to solve for k:
- k = (5.4 x 10^-5 mol L^-1 s^-1) / (0.01 mol L^-1)
- k = 5.4 x 10^-3 s^-1
3. Converting to appropriate units:
- Since k = 5.4 x 10^-3 s^-1 can also be expressed as:
- k = 0.54 x 10^-2 s^-1 = 0.54 L mol^-1 s^-1 (taking into account the units of rate and concentration)
Conclusion
Thus, the rate constant k is 0.54 L mol^-1 s^-1. The correct answer is option 'A'.

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