The reaction is called chain reaction when

a. it is one that can be initiated by light

b. it involves free radicals that have an unusual stability and thereby cause a large quantum yield

c. it involves a series of steps, each of which generates a reactive intermediate that brings about the next step

d. it involves several steps

e. it involves two steps of equal activation energy

c. it involves a series of steps, each of which generates a reactive intermediate that brings about the next step

Explanation:

A chain reaction consist of many repeating steps. Chain reaction will never stop until all the reactant has been exhausted. It is more of a cycle of reaction that generate a reactive intermediate that brings about the next step.

Example of a chain reaction is the chlorination of methane.

CH4 + Cl2  ↔ CH3Cl + HCl

CH3Cl  + Cl2  ↔ CH2Cl2 + HCl

CH2Cl2 + Cl2  ↔ CHCl3 + HCl

CHCl3 + Cl2  ↔ CCl4 + HCl

answer: - 3.) the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

solution: - as per the rules, oxidation number of oxygen in its compounds is -2. the sum of oxidation numbers of all the elements of a molecule or compound is zero.

also, the oxidation number in elemental form is zero.

in no, the oxidation number of o is -2 so the oxidation number of n is +2 so that the sum is zero.

similarly, the oxidation number of c in co is +2 and o is -2.

on product side the oxidation number of n is 0 as it is in the elemental form() .

oxidation number of c in carbon dioxide is +4 as there are two oxygen in it and we know that each oxygen is -2.

so, oxidation number of n is changing from +2 to 0 and the oxidation number of c is changing from +2 to +4.

since nitrogen is reduced and hence no is acting as an oxidizing agent. carbon is oxidized and so co is acting as a reducing agent.

so, the right choice is number 3.)the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

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