Question

Which of the following reactions are possible?
(i) $Mg + CuS{O_4} \to MgS{O_4} + Cu$
(ii) $Ca + MgS{O_4} \to CaS{O_4} + Mg$
(iii) $Cu + ZnS{O_4} \to CuS{O_4} + Zn$
(iv) $Fe + MgS{O_4} \to FeS{O_4} + Mg$
a) $iii$ and $iv$ only
b) $i$ and $iv$ only
c) $ii$ and $iii$ only
d) $i$ and $ii$ only

Answer 1

Chemical reactions are classified into single and double displacement reactions based on the displacement of reactants by one another. The metal with high reactivity can be only able to displace the metal with low reactivity. Simply, high reactive metal displaces low reactive metal.

Complete answer:
Metals can easily undergo loss of electrons and this process is known as oxidation. Some metals like potassium and sodium are highly reactive and react vigorously with water.
The order of reactivity of some metals will be as follows which was started from the high reactivity to least reactivity.
Potassium, sodium, magnesium, aluminum, carbon, zinc, iron, tin, lead, hydrogen, copper, silver, gold, and platinum.
In the option reaction, $Mg + CuS{O_4} \to MgS{O_4} + Cu$
Magnesium can displace copper due to high reactivity of magnesium. Thus, this reaction is possible.
In the option reaction, $Ca + MgS{O_4} \to CaS{O_4} + Mg$
Calcium can displace magnesium due to high reactivity of calcium. Thus, this reaction is possible.
In the reaction, $Cu + ZnS{O_4} \to CuS{O_4} + Zn$
Copper cannot displace zinc due to less reactivity. Thus, this reaction is not possible.
In the reaction, $Fe + MgS{O_4} \to FeS{O_4} + Mg$
Iron cannot displace magnesium due to less reactivity. Thus, this reaction is not possible.
Thus, only the reactions $i$ and $ii$ only are possible.
Option d is the correct one.

Note:
Some elements in the periodic table were represented by their chemical names. For example, iron was represented by $Fe$ , whose chemical name is ferrous. Least reactive metals like gold, silver, and copper also have chemical symbols related to their chemical names only.