Question

Which of the following can dissolve limestone?
A. \[C{O_2}\; + \;{H_2}O\]
B. \[NaO{H_2} + \;{H_2}O\]
C. \[N{H_3}\, + \;{H_2}O\]
D. None of these

Answer 1

Hint:
Limestone is present in solid state at room temperature. The compound \[CaC{O_3}\]is the chemical formula of limestone and its chemical name is calcium carbonate.

Complete step by step solution
We know that, the displacement of the ions of one reactant to another and the new product will form in a double displacement reaction.

The property of limestone is to dissolve in carbon dioxide and water to form calcium hydrogen carbonate. It is easy to know why lime stone will not dissolve in sodium hydroxide and ammonia because it will form a salt by double displacement reaction, which will precipitate out as solid precipitate.

The limestone does not dissolve in water but it will form a solution same as that of mud and water. Two separate layers can be seen. If limestone is mixed with a mixture of carbon dioxide and water. It will form calcium hydrogen carbonate.
The reaction for this is as follows:
\[CaC{O_{3(s)}} + C{O_{2(g)}} + {H_2}{O_{(l)}} \to \;\;Ca{(HC{O_3})_2}_{(aq)}\\ \]
\[CaC{O_3}\left( s \right) + 2NaO{H_{(aq)}} \to Ca{\left( {OH} \right)_{2(aq)}} + N{a_2}C{O_{3(aq)}}\]
In the above reaction, the salt is formed and water gets evaporated as the reaction is exothermic. Hence, the option(B) is not the answer.

\[CaC{O_3}\; + {\rm{ }}2N{H_3}\; \to \;\;CaC{N_2}\; + {\rm{ }}3{H_2}O\;\]
In the above reaction, the salt will be produced. Hence, we can say that option (C) is not appropriate.


Therefore, the answer is option (A) \[C{O_2}\; + \;{H_2}O\]

Note:
The reaction of limestone with water is not possible; it has a property to form sediment. The use of limestone is done in many ways but the most popular is used as paint to cover the walls of the home and protect it from heat.