True statement among the following is:
1. | The rate of a reaction decreases with the passage of time as the concentration of reactants decreases. |
2. | The rate of a reaction is the same at any time during the reaction. |
3. | The rate of a reaction is independent of temperature change. |
4. | The rate of a reaction decreases with an increase in the concentration of the reactants. |
The correct expression for the rate of reaction given below is:
\(5 \mathrm{Br}^{-}(\mathrm{aq})+\mathrm{BrO}_3^{-}(\mathrm{aq})+6 \mathrm{H}^{+}(\mathrm{aq}) \rightarrow 3 \mathrm{Br}_2(\mathrm{aq})+3 \mathrm{H}_2 \mathrm{O}(\mathrm{l})\)
1. | \(\frac{\Delta\left[B r^{-}\right]}{\Delta t}=5 \frac{\Delta\left[H^{+}\right]}{\Delta t} \) | 2. | \(\frac{\Delta\left[\mathrm{Br}^{-}\right]}{\Delta t}=\frac{6}{5} \frac{\Delta\left[\mathrm{H}^{+}\right]}{\Delta t} \) |
3. | \(\frac{\Delta[\mathrm{Br^-}]}{\Delta t}=\frac{5}{6} \frac{\Delta\left[\mathrm{H}^{+}\right]}{\Delta t} \) | 4. | \(\frac{\Delta\left[\mathrm{Br}^{-}\right]}{\Delta t}=6 \frac{\Delta\left[\mathrm{H}^{+}\right]}{\Delta t}\) |
The correct representation of an exothermic reaction is:
1. | 2. | ||
3. | 4. | Both 1 and 2 |
Rate law for the reaction \(A+2 B \rightarrow C\) is found to be
Rate = k[A][B]
If the concentration of reactant 'B' is doubled, keeping the concentration of A constant, then the value of the rate of the reaction will be:
1. | The same. | 2. | Doubled. |
3. | Quadrupled. | 4. | Halved. |
An incorrect statement about the collision theory of chemical reaction is:
1. | It considers reacting molecules or atoms to be hard spheres and ignores their structural features. |
2. | The number of effective collisions determines the rate of reaction. |
3. | The collision of atoms or molecules possessing sufficient threshold energy results in product formation. |
4. | Molecules should collide in the proper orientation for the collision to be effective with sufficient threshold energy and proper orientation. |
A first-order reaction is 50 % completed in 1.26 × 1014 s. The time required for 100 % completion of the reaction will be:
1. 1.26 × 1015 s
2. 2.52 × 1014 s
3. 2.52 × 1028 s
4. Infinite
Compounds A and B react according to the following chemical equation.
A(g) + 2B(g) 2C(g)
The concentration of either A or B was changed keeping the concentrations of one of the reactants constant and rates were measured as a function of initial concentration. The following results were obtained. Choose the correct option for the rate equations for this reaction.
Experiment | Initial concentration of [A]/mol L–1 |
Initial concentration of [B]/moI L–1 |
Initial rate (mol L–1 s–1) |
1. 2. 3. |
0.30 0.30 0.60 |
0.30 0.60 0.30 |
0.10 0.40 0.20 |
An incorrect statement regarding the catalyst is:
1. | It catalyzes the forward and backward reactions to the same extent. |
2. | It alters gibbs free energy of the reaction. |
3. | It is a substance that does not change the equilibrium constant of a reaction. |
4. | It provides an alternate mechanism by reducing activation energy between reactants and products. |
The value of the rate constant of a pseudo-first-order reaction:
1. | Depends on the concentration of reactants present in a small amount. |
2. | Depends on the concentration of reactants present in excess. |
3. | Is independent of the concentration of reactants. |
4. | Depends only on temperature. |
Consider the reaction AB. The concentration of both the reactant and the product varies exponentially with time.
The graph that accurately depicts how reactant and product concentrations change with time is:
1. | 2. | ||
3. | 4. |