Question

Zinc metal is added to aluminium sulphate solution, no reaction takes place because:
(A) Aluminium is more reactive than zinc
(B) Aluminium and zinc both are unreactive
(B) Aluminium is less reactive than zinc
(D) None of these

Answer 1

Hint:
The displacement reaction is a chemical reaction in which one element is being replaced by another element in a compound. This displacement reaction can occur if we allow a strong element to replace a weaker element.

Complete step by step answer:
The displacement reactions are those reactions in which one element gets displaced from its position and the other element takes its position and forms a new compound. Now, it is to be noted that this displacement can only occur if a strong element is allowed to displace a weak element. This can be decided with the help of the reactivity series. The reactivity series states the order of metals from strong to the weak elements. The reactivity series in the decreasing order of reactivity of elements is given below:
$Li > K > Sr > Na > Ca > Mg > Al > Zn > Cr > Fe > Cd > Co > Ni > Sn > Pb > H > Sb > As > Bi > $
$Cu > Hg > Ag > Pd > Pt > Au$.
From this reactivity series, we can conclude that lithium $(Li)$ strong, we can conclude that lithium $(Au)$ is the weakest element among all.
We already know that the strong elements can replace the weak elements. Similarly we can say that, the elements having high reactivity is the stronger element can easily displace the weaker elements which have low reactivity.
Thus, it is crystal clear from the given reactivity series that the elements appearing first have high reactivity and can easily displace the elements which are positioned below them or if the elements have low reactivity.
From the above discussion we can say that if we add zinc metal to the aluminium sulphate solution. Then no reaction would take place. This is because the zinc is placed below the aluminium in the reactivity series or in simple words. Aluminium is stronger than zinc and also, aluminium is more reactive than zinc would not be able to displace the aluminium from its position.

Hence, the answer is option (A).

Note: Due to the free nature of the reactants, all displacement reactions are considered to be oxidation reduction reactions, which allow the movements of electrons from one reactant to the other. More ever, the reactant elements may have different charges as ions thus it is necessary to balance these equations.