Single Choice

Zn gives hydrogen gas with $$ H_2SO_4 $$ and $$HCl$$ but not with $$ HNO_3 $$ because

A$$ NO_3^- $$ is reduced in preference to $$ H_3O^+ $$
Correct Answer
B$$ HNO_3 $$ is weaker acid than $$ H_2SO_4 $$ and $$HCl$$
CZn acts as oxidising agent when reacts with $$ HNO_3 $$
DIn electrochemical series Zn is placed above the hydrogen

Solution

Zinc gives H2 gas with dil. H2SO4/HCl but not with HNO3 because in HNO2, NO
−
3
ion is reduced and gives NH
+
4
, N2O, NO and NO2 (based upon the concentration of HNO3)

4Zn+dil. 10HNO3→4Zn(NO3)2+NH4NO3+3H2O

HNO3 is an oxidising agent. Hydrogen obtained in this reaction is converted into H2O.

Zn is on the top position of hydrogen in electrochemical series. So Zn displaces H2 from dilute H2SO4 and HCl with liberation of H2.

SIMILAR QUESTIONS

Metals and Non - metals

Iron is rendered passive by treatment with concentrated:

Metals and Non - metals

(a) Explain why metals usually do not liberate hydrogen gas with dilute nitric acid. (b) Name two metals which can however, liberate hydrogen gas from very dilute nitric acid.

Metals and Non - metals

(a) What happens when calcium reacts with chlorine? Write an equation of the reaction which takes place. (b) What happens when magnesium reacts with very dilute acid? Write an equation for the reaction involved.

Metals and Non - metals

Very dilute nitric acid reacts with iron to produce hydrogen.

Metals and Non - metals

The metal which reacts with $$HNO_{3}$$ to give five different products depending upon the concentration of the acid is :

Metals and Non - metals

Carbon can reduce copper oxide to copper but not CaO to Ca. Why?

Metals and Non - metals

Pure conc. $$ HNO_3 $$ makes iron passive as the surface is covered with protective layer of

Metals and Non - metals

Iron when treated with concentrated nitric acid

Metals and Non - metals

Hot and conc. nitric acid when reacts with copper, the gas obtained is

Metals and Non - metals

Reaction of zinc with cold and very dilute nitric acid yields

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