Question

Li, K, Ca, Na, Mg, Al, Zn, Fe, Pb, Cu, Hg, Ag
I. The reaction $Z{{n}_{\left( s \right)}}+Cu{{\left( N{{O}_{3}} \right)}_{2\left( aq \right)}}\to C{{u}_{\left( s \right)}}+Zn{{\left( N{{O}_{3}} \right)}_{2\left( aq \right)}}$ will occur.
II. Zinc and copper both are transition metals.
(A) Statement I is true, Statement II is true
(B) Statement I is true, Statement II is false
(C) Statement I is false, Statement II is true
(D) Statement I is false, Statement II is false

Answer 1

Hint: Take a look at the reactivity series of metals given in the question. It is given in the decreasing order that is, lithium is most reactive and silver is the least reactive. Locate the position of metals taking part in the reaction and then come to conclusion whether the given reaction will occur or not. Recollect what transition metals are and to which block they belong to get the answer for the second statement.

Complete step by step answer:
- Let’s first discuss statement 1. There is a reactivity series of metals which is given and it says the given reaction will take place. So, we need to check whether the statement holds true.

- The reactivity order of metals is
Li > K > Ca > Na > Mg > Al > Zn > Fe > Pb > Cu > Hg > Al

- The given reaction is,
\[Z{{n}_{\left( s \right)}}+Cu{{\left( N{{O}_{3}} \right)}_{2\left( aq \right)}}\to C{{u}_{\left( s \right)}}+Zn{{\left( N{{O}_{3}} \right)}_{2\left( aq \right)}}\]

- In this reaction, zinc is reacting with cuprous nitrate to form copper metal and zinc nitrate.
- From the reactivity series of metals, we can see that zinc is more reactive than copper. So, zinc will readily get oxidized to form zinc nitrate. Copper having less reactivity will just accept electrons and get reduced back to metallic state. Therefore, statement I is true.

- Let’s take a look at statement II. It says, zinc and copper are transition metals.
- Transition metals are metals present in the d-block of periodic tables. Transition metals are elements in the d-block of a periodic table which can show d-d transitions.
- Zinc has atomic number 30 and copper has atomic number 29. They have the electronic configurations, ${}^{30}Zn=\left[ Ar \right]3{{d}^{10}}4{{s}^{2}}$ and ${}^{29}Cu=\left[ Ar \right]3{{d}^{9}}4{{s}^{2}}=\left[ Ar \right]3{{d}^{10}}4{{s}^{1}}$

- We can see that zinc has completely filled 3d orbitals so there is no scope for d-d transition. Copper has incompletely filled 3d orbitals so there is a possibility of d-d transition.
- So, zinc is not a transition element but it is referred to as a post-transition element. Copper is a transition element. Therefore, statement 2 is false.
So, the correct answer is “Option B”.

Note: Remember although zinc belongs to d-block, it is not a transition metal due to completely filled d-orbitals. Zinc is more reactive than copper. So, zinc will get oxidized to form zinc electrolyte and copper will get reduced to copper metal. During the electrolytic process, zinc will form anode and copper will form cathode.