Question

Gas released in the following reaction will be:
\[{\text{Na}} + {\text{HN}}{{\text{O}}_{\text{3}}}{\text{(dil)}} \to \]
A.Oxygen
B.Hydrogen
C.Nitrogen
D.Nitrogen dioxide

Answer 1

Hint:We know that Sodium is a metal while nitric acid is a strong acid as well as a strong oxidizing agent. To answer this question, you must recall the reaction occurring between an acid and metal. The gas released is used for reduction of unsaturated hydrocarbons.

Complete answer:
The reaction between an acid and a metal is a simple displacement reaction. Nitric acid in this case is an oxidizing agent as it being an acid releases a proton. Nitric acid is a monobasic acid, i.e., one molecule of the acid releases only one hydrogen ion. The hydrogen ion released from the acid is replaced by the metal.
The metal given in the above reaction is sodium metal which has a strong ability to donate electrons and get converted into a positive ion. The electron released by the metal is taken up by the hydrogen ion whereas, the metal forms a salt with the conjugate base of the acid since it is a good oxidizing agent and has a tendency to accept the electrons and form a bond with the metal.
When two molecules of the metal react with two molecules of the acid, two atoms of hydrogen are produced, and as a result hydrogen gas is released.
The reaction occurring can be given as:
\[{\text{Na}} + {\text{HN}}{{\text{O}}_{\text{3}}}{\text{(dil)}} \to {\text{NaN}}{{\text{O}}_3} + {{\text{H}}_2} \uparrow \]

Thus, the correct answer is B.
Note:
This reaction between a metal and an acid resulting into the formation of hydrogen gas is a commonly used reaction for finding out if a given substance is a metal or not. Metals in combination with acid release hydrogen gas which is observed as an effervescence in the solution. If a burning matchstick is brought close to the test tube, it burns with a pop sound due to hydrogen gas.