Which of the following Halogens react fast with alkanes in substitution reactions?
Correct answer: B. F2
- A. Cl2
- B. F2
- C. I2
- D. Br2
Explanation
Fluorine (F) is the most reactive halogen and therefore reacts faster with alkanes in substitution reactions. This is because fluorine has the smallest atomic radius and highest electronegativity of all the halogens, making it highly reactive and able to break the strong carbon-hydrogen bonds in alkanes. F2 > Cl2 > Br2 > I2 The reactivity of halogen decreases in this order. Hence this is the only correct option.
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About Free Radical Substitution
Free radical substitution explains how alkanes react with halogens under ultraviolet light or heat through initiation, propagation and termination steps. The mechanism involves homolytic bond fission and radical intermediates, while product formation depends on the relative stability of radicals and differs from ionic substitution.
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