✔ 最佳答案
25.
A more reactive metal can displace a less reactive metal from its salt.
However, a less reactive metal cannot displace a more reactive metal.
When nickel (Ni) is put into the three solutions, nickel can displace P, but cannot displace Q and R. This means that nickel is more reactive than P but less reactive than Q and R.
Reactivity : (Q, R) > Ni > P ...... [1]
When iron (Fe) is put into the three solutions, iron can displace P and Q, but cannot displace R. This means that iron is more reactive than P and Q, but less reactive than R.
Reactivity : R > Fe > (P, Q) ...... [2]
Combining [1] and [2], the reactivity : R > Fe > Q > Ni > P
...... The answer is : B. R, Fe, Q, Ni, P