Question

What happens in a single displacement reaction ?

Answer 1

The reactions which involve the replacement of one reactant with the element of another reactant are said to be displacement reactions. Now using this you can easily answer the statement accordingly.

Complete answer:
First, we should know what a chemical reaction is. The reaction in which the reactants react with each other to form two or more products is known as the chemical reaction. The reactants are written on the left hand side and the products are written on the right-hand side and there is an arrow from left to the right symbolizing a complete chemical reaction.
Example: consider the general reaction as:
$A+B\to C+D$
Here, A and B are the reactants and C and D are the products and the arrow indicates the direction in which the chemical reaction occurs.
Now considering the statement as;
Single displacement reactions are those reactions in which one element displaces the other element from its compound.
Consider the general reaction as:-
$A+BC\to AB+C$
Example:-
$2HCl(aq)+Zn(s)\to ZnC{{l}_{2}}(aq)+{{H}_{2}}(g)$
Conditions for the single displacement reactions are;-

1. Only a more reactive element can displace the other element from its compound.
2. A metal always displaces a metal and a nonmetal always displaces a non-metal.

Note:
Don’t get confused in the single and double displacement reactions. In single displacement reaction; one element replaces the other element from its compound whereas on the other hand in double displacement reaction; the positive and the negative ions of the two reactants involved in the chemical reactions exchange their positions.
Consider the general reactions as;-
For single displacement:-
$A+BC\to AB+C$
For double displacement:-
$AB+CD\to AC+BD$