Question

During halogenation of alkanes, the halogens and alkane show a specific trend. Which of the following statements is not correct?
The reactivity of halogens is in the order ${F_2} > C{l_2} > B{r_2} > {I_2}$
For a given halogen the reactivity of hydrocarbons is in the order of \[{3^0} > {2^0} > {1^0}\]
Bromine is less reactive than chlorine towards a particular alkane.
On chlorination monosubstituted products are formed while on bromination disubstituted products are formed.

Answer 1

Hint: To solve this problem we will firstly define the halogenation process and then the trends which halogen and alkanes show while going through this reaction. Halogenation reaction is a chemical reaction between a substance and a halogen in which the substance incorporates one or more halogen atoms into its molecules. Now we discuss both the terms and will reach the answer.

Complete step by step solution:
 Halogenation of Alkanes-
Halogenation of an alkane produces a hydrocarbon derivative in which hydrogen atoms were replaced by one or more halogen atoms.
Alkanes are notoriously unreactive compounds, since they are non-polar and lack functional groups where reactions can occur. Therefore free radical halogenation provides a method through which alkanes can be functionalized. However, the number of similar C-H bonds present in all but the simplest alkanes is a severe limitation of radical halogenation, so selective reactions are difficult to attain.
Halogens are highly reactive, and can in sufficient quantities be harmful or lethal to biological organisms. By reacting with atoms of other elements Halogens can gain an electron.
The reactivity order of halogen group is ${F_2} > C{l_2} > B{r_2} > {I_2}$
The number of halogen substituents on alkanes also depends on the number of different types of replaceable hydrogen atoms in the alkanes, not on the halogen. Thus the same number of substitutions will be given by chlorine and bromine.
From the above discussion it is clear that the correct option is A.


Note: In order to solve questions related to the group of atoms or about its reactivity, you need to have a clear understanding about the reactivity series of the element. In the above group the fluorine is the most reactive element. Also, the chlorine could displace bromine and iodine, bromine could only displace iodine, but iodine could not displace chlorine or bromine due to the relative reactive strength between them.