Question

Which of the following is a displacement reaction?
A.$S+{{O}_{2}}\to S{{O}_{2}}$
B.$KCl{{O}_{3}}\to KCl+{{O}_{2}}$
C.$Ca+{{H}_{2}}O\to Ca{{(OH)}_{2}}+{{H}_{2}}$
D.${{F}_{2}}+O{{H}^{-}}\to {{F}^{-}}+O{{F}_{2}}+{{H}_{2}}O$

Answer 1

Displacement reaction is the reaction where a higher reactive species displaces lower reactive species. . For example, the below given reaction is a displacement reaction in which the higher reactive species is represented as A and the lower reactive species as B.
A replaces B in the reaction, $A+BC\to B+AC$

Complete answer:
-Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound. The metals and non-metals, both categories, take part in the displacement reaction. There are two types of displacement reaction-
(a) Single displacement reaction: Here single replacement takes place,$A+BC\to B+AC$
For example:$C{{l}_{2}}+2NaBr\to 2NaCl+B{{r}_{2}}$
(b) Double displacement reaction: Here two ionic compounds exchange between them and form two new compounds,$AB+CD\to CB+AD$ $AB+CD\to CB+AD$
For example:$BaC{{l}_{2}}+2NaS{{O}_{4}}\to BaS{{O}_{4}}+2NaCl$
The first option (A) that is preparation of sulphur dioxide is a combination (synthesis) combustion process.
The second option (B) that is potassium chlorate decomposition is an example of decomposition reaction.
The third option (C) that is Calcium hydroxide production is a combination (synthesis) reaction.
In the fourth option (D) fluorine replaces hydride ion thus it is a displacement reaction. According to the reactivity series the halogens with the highest propensity to acquire electrons are the most reactive so fluorine is more reactive than hydride ion and it replaces hydride ion and forms oxo halide and halide compounds.
Displacement reaction largely used for extracting metals.
The fluoride transfer is the example of displacement reaction and thus option D is the correct

Note:
This type of reaction is also called as disproportionation reaction where fluorine is both oxidized and reduced simultaneously in one reaction:
$\overset{0}{\mathop{{{F}_{2}}}}\,+O{{H}^{-}}\to \overset{-1}{\mathop{F}}\,\,+O\overset{+1}{\mathop{{{F}_{2}}}}\,\,+{{H}_{2}}O$
The displacement reactions are generally observed when the chemical reactions like oxidation or reduction reactions occur between the ionic compounds. Displacement reactions find many applications in extraction and processing of metals etc.