List of top Chemistry Questions

$t_{1/2}$ for a first order reaction is $14.26\, min$. Calculate the time when $5\%$ of the reactant is left.
99% of a first order reaction was completed in 32min. When will 99.9% of the reaction complete ?
A first order reaction is $20\%$ complete in $10$ minutes. What is the specific rate constant for the reaction?
A first order reaction is $50$% complete in $30$ minutes at $27?C $ and in $10$ minutes at $47?C$. The reaction rate constant at $27?C$ and the energy of activation of the reaction are respectively
A first order reaction takes $40$ min for $30\%$ decomposition. What will be $t_{1/2}$?
A following mechanism has been proposed for a reaction 2A + B$\to$ D + EA + B$\to$ C + D (slow)A + C $\to$ E (fast) .The rate law expression for the reaction is
A reaction is 50% complete in 2 hours and 75% complete in 4 hours the order of reaction is
A schematic plot of ln $k_{eq}$ versus inverse of temperature for a reaction is shown in the figure. The reaction must be
A substance A decomposes in solution following the first order kinetics. Flask I contains 1 L of 1 M solution of A and flask II contains 100 mL of 0.6 M solution. After 8 hr the concentration of A what will be the timefor concentration of A in flask II to become 0.3 M
A substance undergoes first order decomposition. The decomposition follows two parallel first order reactions as : $If k_{1}=1.26\times10^{-4} s^{-1}, k_{2}=3.8 \times10^{-5} s^{-1},$ then the percentage distributions of B and C are respectively
A zero order reaction is one whose rate is independent of
Among the following reactions, the fastest one is
Order of a reaction with respect to any reactant can be zero, positive, negative or fractional Rate of a reaction cannot decrease with increase in concentration of a reactant or a product.
In a pseudo first order hydrolysis of ester in water, the following results were obtained. What will be the average rate of reaction between the time interval $30$ to $60$ seconds?
Collision theory is applicable to
Consider the reaction Consider the reaction $A$ $\rightarrow$ $B$. The concentration of both the reactants and the products varies exponentially with time. Which of the following figures correctly describes the change in concentration of reactants and products with time?
For a hypothetical reaction A$\to$ B, the rate constant is $0.25\, sec^{-1.}$ If the concentration of A is reduced to half, then the value of rate constant is
For a pseudo first order reaction, $CH_{3}COOC_{2}H_{5}+H_{2}O $ $ { <=>[H^{+}] }$ $CH_{3}COOH+C_{2}H_{5}OH$ the net rate is given by $\frac{d x}{d t}=4\times10^{-4} L mol^{-1} s^{-1} \left[\left(CH_{3}COOC_{2}H_{5}\right)\right]-3\times10^{4}L \, mol^{-1} s^{-1}\left[CH_{3}COOH\right]\left[C_{2}H_{5}OH\right]$ Then, the equilibrium constant of the reaction would be
For a second order reaction in which both the reactants have equal initial concentration, the time taken for 20% completion of reaction is 500 second. What will be the time taken for 60% of the reaction?
For the reaction $4A + B \to 2C + 2D,$ which of the following statements is not correct
From the above figure, the activation energy for the reverse reaction would be
Half life period of 2nd order reaction is
Half-life period of a first order reaction is $10$ min. What percentage of the reaction will be completed in $100$ min?
If initial concentration is doubled, the time for half reaction is also doubled, the order of reaction is
In acidic medium, the rate of reaction between $[BrO_{3}]$ and $[Br^{-}]$ ions is given by the expression $-\frac{d \left[BrO_{3}^{-}\right]}{d t}=k\left[BrO_{3}^{-}\right]\left[Br^{-}\right]\left[H^{+}\right]^{2}$ It means (i) rate constant of the reaction depends upon the concentration of $H^{+}$ ions (ii) rate of reaction is independent of the concentration of acid added (iii) the change in $pH $ of the solution will affect the rate of reaction (iv) doubling the concentration of $H^{+}$ ions will increase the reactions rate by 4 times.