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Read the passage given below and answer the questions that follow : The rate law for a chemical reaction relates the reaction rate with the concentrations or partial pressures of the reactants. For a general reaction aA + bB → C with no intermediate steps in its reaction mechanism, meaning that it is an elementary reaction, the rate law is given by r = k[A]x[B]y, where [A] and [B] express the concentrations of A and B in moles per litre. Exponents x and y vary for each reaction and are determined experimentally. The value of k varies with conditions that affect reaction rate, such as temperature, pressure, surface area, etc. The sum of these exponents is known as overall reaction order. A zero order reaction has a constant rate that is independent of the concentration of the reactants. A first order reaction depends on the concentration of only one reactant. A reaction is said to be second order when the overall order is two. Once we have determined the order of the reaction, we can go back and plug in one set of our initial values and solve for k.
Answer the following questions (Do any two) :
Observe the graph shown in figure and answer the following questions :
The variation in the concentration (R) vs. time (t) plot is given below. Answer the following questions on the basis of the given figure :
Given below is the decomposition of hydrogen peroxide in alkaline medium, which is catalysed by iodide ions : 2H₂O₂ → 2H₂O + O₂ (I⁻, alkaline medium). The above reaction takes place in two steps : Step I : H₂O₂ + I⁻ → H₂O + IO⁻ (slow). Step II : H₂O₂ + IO⁻ → H₂O + I⁻ + O₂. Molecularity of Step I and Step II is :
Assertion (A) : Hydrolysis of an ester in acidic medium is a second order reaction. Reason (R) : For a complex reaction, order is given by the slowest step.
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