Answer :
(A) The balanced molecular equation will be:
![K_2CO_3(aq)+Pb(NO_3)_2(aq)\rightarrow 2KNO_3(aq)+PbCO_3(s)](https://tex.z-dn.net/?f=K_2CO_3%28aq%29%2BPb%28NO_3%29_2%28aq%29%5Crightarrow%202KNO_3%28aq%29%2BPbCO_3%28s%29)
(B) The balanced molecular equation will be:
![Li_2SO_4(aq)+Pb(CH_3COOH)_2(aq)\rightarrow 2LiCH_3COOH(aq)+PbSO_4(s)](https://tex.z-dn.net/?f=Li_2SO_4%28aq%29%2BPb%28CH_3COOH%29_2%28aq%29%5Crightarrow%202LiCH_3COOH%28aq%29%2BPbSO_4%28s%29)
(C) The balanced molecular equation will be:
![Cu(NO_3)_2(aq)+Na_2S(aq)\rightarrow 2NaNO_3(aq)+CuS(s)](https://tex.z-dn.net/?f=Cu%28NO_3%29_2%28aq%29%2BNa_2S%28aq%29%5Crightarrow%202NaNO_3%28aq%29%2BCuS%28s%29)
(D) The balanced molecular equation will be:
![Sr(NO_3)_2(aq)+2KI(aq)\rightarrow \text{No reaction}](https://tex.z-dn.net/?f=Sr%28NO_3%29_2%28aq%29%2B2KI%28aq%29%5Crightarrow%20%5Ctext%7BNo%20reaction%7D)
Explanation :
Molecular equation : It is defined as a balanced chemical equation where the ionic compounds are expressed in the form of molecules rather than component of ions.
Precipitation reaction : It is defined as the reaction in which an insoluble salt formed when two aqueous solutions are combined.
The insoluble salt that settle down in the solution is known an precipitate.
Part A : potassium carbonate and lead(II) nitrate
The balanced molecular equation will be:
![K_2CO_3(aq)+Pb(NO_3)_2(aq)\rightarrow 2KNO_3(aq)+PbCO_3(s)](https://tex.z-dn.net/?f=K_2CO_3%28aq%29%2BPb%28NO_3%29_2%28aq%29%5Crightarrow%202KNO_3%28aq%29%2BPbCO_3%28s%29)
In this reaction, lead carbonate is an insoluble salt and potassium nitrate is a soluble solution.
Part B : lithium sulfate and lead(II) acetate
The balanced molecular equation will be:
![Li_2SO_4(aq)+Pb(CH_3COOH)_2(aq)\rightarrow 2LiCH_3COOH(aq)+PbSO_4(s)](https://tex.z-dn.net/?f=Li_2SO_4%28aq%29%2BPb%28CH_3COOH%29_2%28aq%29%5Crightarrow%202LiCH_3COOH%28aq%29%2BPbSO_4%28s%29)
In this reaction, lead sulfate is an insoluble salt and lithium acetate is a soluble solution.
Part C : copper(II) nitrate and sodium sulfide
The balanced molecular equation will be:
![Cu(NO_3)_2(aq)+Na_2S(aq)\rightarrow 2NaNO_3(aq)+CuS(s)](https://tex.z-dn.net/?f=Cu%28NO_3%29_2%28aq%29%2BNa_2S%28aq%29%5Crightarrow%202NaNO_3%28aq%29%2BCuS%28s%29)
In this reaction, Cuprous sulfide is an insoluble salt and sodium nitrate is a soluble solution.
Part D : strontium nitrate and potassium iodide
The balanced molecular equation will be:
![Sr(NO_3)_2(aq)+2KI(aq)\rightarrow 2KNO_3(aq)+SrI_2(aq)](https://tex.z-dn.net/?f=Sr%28NO_3%29_2%28aq%29%2B2KI%28aq%29%5Crightarrow%202KNO_3%28aq%29%2BSrI_2%28aq%29)
In this reaction, strontium iodide and potassium nitrate are soluble solution.
![Sr(NO_3)_2(aq)+2KI(aq)\rightarrow \text{No reaction}](https://tex.z-dn.net/?f=Sr%28NO_3%29_2%28aq%29%2B2KI%28aq%29%5Crightarrow%20%5Ctext%7BNo%20reaction%7D)