Question

What is the balanced answer for $Cu + dil{\text{ }}HN{O_3} \to$ ?
A) $Cu{(N{O_3})_2}$
B) $Cu{(N{O_3})_2} + N{O_2} + {H_2}O$
C) $N{O_2}$
D) None of these

Answer 1

We have to remember that balancing the chemical reaction is the best way to solve these types of questions. We have to also know that this type of reaction is an oxidation reduction type, one can also confuse this type of reaction as displacement reaction, but before answering the question look at the options carefully.

Complete answer:
We also need to know that this reaction is a type of oxidation and reduction reaction taking place simultaneously in which gaining electrons reduces an element and losing an electron oxidizes them.
$HN{O_3}$, Nitric acid behaves as strong acid in this type of reaction and behaves as a strong oxidizing agent as it oxidizes $Cu$ into $C{u^{2 + }}$.
$N{O_3}^ -$, Nitrate ion makes $Cu$ to dissolve
We also remember that the $Cu$ is an unreactive metal and it generally doesn’t react with dilute acids, and here $HN{O_3}$ behaves as an oxidizing agent.
Option A) this is an incorrect option as we cannot get the balanced chemical equation
$Cu + dil.HN{O_3} \to Cu{(N{O_3})_2}$
Option B) this is a correct option, as this chemical equation is a completely balanced equation.
$Cu + dil.HN{O_3} \to Cu{(N{O_3})_2} + N{O_2} + {H_2}O$
Option C) this is an incorrect option, as this chemical equation is not possible
$Cu + dil.HN{O_3} \to N{O_2}$
Option D) this is an incorrect option as we get the correct answer as Option B.

Note:
To get the chemical equation solved, we must balance the chemical reaction which makes the question easy to answer. Also answering this question one must should have the good knowledge of type of chemical reactions i.e. Addition, Displacement, Decomposition and other reactions.