MolSynapse / Question bank / Surface Chemistry / Catalysis: homogeneous, heterogeneous, enzyme catalysis

Catalysis: homogeneous, heterogeneous, enzyme catalysis

55 questions on Catalysis: homogeneous, heterogeneous, enzyme catalysis from the Surface Chemistry chapter: 11 NEET level, 22 JEE Main, 22 JEE Advanced. Each one opens with its answer and solution.

Practice this topic All Surface Chemistry topics

A catalyst increases the rate of a chemical reaction mainly because it NEET level
Which of the following is an example of homogeneous catalysis? NEET level
Enzymes are chemically NEET level
The enzyme urease catalyses NEET level
In the Ostwald process for nitric acid, the catalyst used in the oxidation of ammonia is NEET level
A catalyst does not change NEET level
A substance that reduces or destroys the activity of a catalyst is called a NEET level
In the Haber process, molybdenum is added to the iron catalyst in order to NEET level
In the titration of oxalic acid with acidified KMnO4 at about 330 K the decolourisation is slow at first and then becomes fast. This is due to NEET level
The catalyst used to convert alcohols directly into gasoline (a mixture of hydrocarbons) is NEET level
Most enzymes of the human body show maximum activity at about NEET level
For a reversible reaction at equilibrium, adding a suitable catalyst JEE Main level
Consider: (i) acid hydrolysis of an ester in aqueous HCl, (ii) decomposition of H2O2 on Pt black, (iii) oxidation of SO2 with NO in the lead chamber, (iv) hydro... JEE Main level
For an enzyme reaction obeying v = dfracV_max[S]K_m + [S], when [S] gg K_m the rate is JEE Main level
A competitive inhibitor of an enzyme JEE Main level
Which of the following enzyme-reaction pairs is wrongly matched? JEE Main level
Assertion (A): A solid catalyst used in a heterogeneous reaction is usually taken in finely divided form. Reason (R): Finely dividing the solid increases its su... JEE Main level
According to the adsorption theory of heterogeneous catalysis, the correct sequence of events is JEE Main level
Which statement about catalysts is INCORRECT? JEE Main level
In the Haber process the catalyst, its promoter and a common poison are, respectively, JEE Main level
The rate of an enzyme-catalysed reaction plotted against temperature JEE Main level
Which catalyst-process pair is wrongly matched? JEE Main level
Zeolites act as shape-selective catalysts because JEE Main level
A reaction has E_a = 100 kJ mol^-1 without a catalyst and 75 kJ mol^-1 with a catalyst, with the same pre-exponential factor. At 300 K, calculate log_10(k_cat/k... JEE Main level
At 298 K a catalyst makes a reaction exactly 10^4 times faster, with no change in the pre-exponential factor. By how many kJ mol^-1 does it lower the activation... JEE Main level
In a catalytic hydrogenation, 0.180 mmol of catalyst converts benzene into 33.6 g of cyclohexane (C6H12, M = 84 g mol^-1). Calculate the turnover number (moles ... JEE Main level
A catalyst sample of 0.0040 mol of active sites produces 3.1 mol of product in 45 min at constant rate. Calculate the turnover frequency in min^-1 (mol of produ... JEE Main level
A first-order reaction without catalyst gives 12.0% conversion in 2.00 h. A catalyst raises the rate constant 25-fold. What percent conversion is reached in 2.0... JEE Main level
An enzyme obeys v = dfracV_max[S]K_m+[S] with V_max = 120 muM min^-1 and K_m = 3.2 mM. Find v (in muM min^-1) at [S] = 5.6 mM, to two decimals. JEE Main level
For an enzyme with K_m = 3.2 mM obeying v = V_max[S]/(K_m+[S]), at what substrate concentration (in mM) is v = 0.40 V_max? Give two decimals. JEE Main level
A 1.0 g sample of a metal catalyst has 1.8 x 10^19 active sites and forms 0.0150 mol of product per minute. Calculate the turnover frequency in s^-1 (molecules ... JEE Main level
Select all correct statements about a catalyst. JEE Main level
Select all correct statements about enzymes. JEE Main level
An exothermic reaction (Delta H = -40 kJ mol^-1) has E_a = 100 kJ mol^-1 for the forward step without a catalyst. A catalyst lowers the forward E_a to 75 kJ mol... JEE Advanced level
An enzyme has K_m = 2.0 mM. In the presence of a competitive inhibitor ([I] = 3.0 mM, K_i = 1.5 mM) the apparent Michaelis constant is K_m^app = K_m(1+[I]/K_i) ... JEE Advanced level
A catalyst bed produces 8.0 mol of product per hour when fresh. After a poison blocks 70% of its active sites, the rate is proportional to the fraction of free ... JEE Advanced level
A catalyst lowers the activation energy of a reaction from 80 kJ mol^-1 to 60 kJ mol^-1 without changing the pre-exponential factor. The catalysed rate constant... JEE Advanced level
Assertion (A): For a gas reacting on a solid catalyst, the rate increases linearly with gas pressure at all pressures. Reason (R): The number of active sites on... JEE Advanced level
A double-reciprocal (Lineweaver-Burk) plot of 1/v against 1/[S] for an enzyme is a straight line with slope 0.150 and intercept 0.0250 (with v in muM min^-1 and... JEE Advanced level
Consider: (i) a catalyst lowers the activation energy of a reaction, (ii) a catalyst increases the equilibrium yield of products, (iii) sucrose inversion cataly... JEE Advanced level
A catalyst lowers the activation energy of a reaction from 96 kJ mol^-1 to 62 kJ mol^-1 but also lowers the pre-exponential factor to 0.010 times its original v... JEE Advanced level
An enzyme lowers the activation energy of a reaction from 90 kJ mol^-1 to 45 kJ mol^-1 at 310 K with equal pre-exponential factors. Calculate the power of ten x... JEE Advanced level
An enzyme has V_max = 80 muM min^-1 and K_m = 4.0 mM. A competitive inhibitor at [I] = 2.0 mM with K_i = 1.0 mM is added. Using K_m^app = K_m(1+[I]/K_i) and v =... JEE Advanced level
Carbonic anhydrase (M = 30000 g mol^-1) has a turnover number k_cat = 6.0 x 10^5 s^-1 (substrate molecules per enzyme per second at saturation). Assuming satura... JEE Advanced level
A solid catalyst site has an initial turnover frequency of 50 s^-1. The catalyst deactivates by first-order decay of activity with a half-life of 20 min. The to... JEE Advanced level
The observed first-order rate constant of an ester hydrolysis follows k_obs = k_0 + k_H[H+]. It is 0.95 x 10^-4 s^-1 at [H+] = 0.050 M and 3.50 x 10^-4 s^-1 at ... JEE Advanced level
An enzyme obeys v = V_max[S]/(K_m+[S]) with V_max = 100 muM min^-1 and K_m = 5.0 mM. Select all correct statements. JEE Advanced level
A catalyst lowers E_a of a reaction from 80 to 50 kJ mol^-1 with no change in the pre-exponential factor (R = 8.314 J mol^-1K^-1). Select all correct statements... JEE Advanced level
Select all correct statements about heterogeneous catalysis. JEE Advanced level
Select all correct statements about enzyme inhibition. JEE Advanced level
Select the reactions that are autocatalytic. JEE Advanced level
In a run, 0.0200 mmol of catalyst forms 7.50 mmol of product in 25 min. Select all correct statements. JEE Advanced level
For a gas reacting on a solid surface with rate r = (kKP)/(1+KP) and K = 0.50 atm^-1, the apparent order with respect to the gas is n = 1/(1+KP). Select all cor... JEE Advanced level
Select all correct statements about enzymes. JEE Advanced level
Catalysts X and Y lower E_a of a reaction from 90 to 60 and 70 kJ mol^-1 respectively, with equal pre-exponential factors. Take R = 8.314 J mol^-1K^-1. Select a... JEE Advanced level