Answer:
a) Y³⁺ > Eu²⁺ > Fr⁺ > Sr²⁺
b) Sr > Fr > Eu > Y
Explanation:
Y is the least reactive metal because it does not react with any of the other solutions.
Sr is the most reactive metal because it reacts with all of the other solutions.
Sr + 2Fr⁺ ⟶Sr²⁺ + 2Fr
3Sr + 2Y³⁺ ⟶ 2Sr²⁺ + 2Y
Sr + Eu²⁺ ⟶ Sr²⁺ + Eu
Fr is more reactive than Eu because it reacts with Eu(NO₃)₂.
2Fr + Eu²⁺ ⟶ 2Fr⁺ + Eu
The order of reactivity is
Sr > Fr > Eu > Y
b) Reducing agents
In each of the above reactions. the more reactive metal is acting as a reducing agent — it is donating electrons to the cation of the other metal.
Thus, the order of activity of reducing agents is
Sr > Fr > Eu > Y
a) Oxidizing agents
The metal cations are the oxidizing agents.
The order of reactivity of the oxidizing agents is the reverse order of the reducing agents
Y³⁺ > Eu²⁺ > Fr⁺ > Sr²⁺
c) Standard reduction potential table
See the image below.