Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • Engineering
  • Answer please! Which of the following is a redox reaction?

Which of the following is a redox reaction?

  • Option 1)

    NaCI+KNO_{3}\rightarrow NaNO_{3}+KCI

  • Option 2)

    CaC_{2}O_{4}+2HCI\rightarrow CaCI_{2}+H_{2}C_{2}O_{4}

  • Option 3)

    Mg(OH)_{2}+2NH_{4}CI\rightarrow MgCI_{2}+2NH_{4}OH

  • Option 4)

    Zn+2AgCN\rightarrow 2Ag+Zn(CN)_{2}

 

Answers (1)

best_answer

As we learnt in

Redox Reaction -

Redox reaction as a class of reactions in which oxidation and reduction reactions occur simultaneously.

-

 

 and, 

 

 

Oxidation Number -

Oxidation number denotes the oxidation state of an element in a compound ascertained according to a set of rules formulated on the basis that electron pair in a covalent bond belongs entirely to more electronegative elements.

-

 

In a Redox Reaction,  the oxidation states of the constituents should change. 

Keeping that in mind, let us look at each reaction:

\overset{+1}{Na}\overset{-1}{Cl} +\overset{H}{K}\overset{+5}{N}\overset{-2}{O}_{3}\rightarrow\overset{+1}{Na}\overset{+5}{N}\overset{-2}{O}+\overset{+1}{K}\overset{-1}{Cl}

Clearly, there is no change in the oxidation states. 

\overset{2+}{Ca}\overset{+3}{C}_{2}\overset{-2}{O}_{4}\:+\:2\overset{+1}{H}\overset{-2}{Cl}\rightarrow\overset{2+}{Ca}\overset{-1}{Cl}+\overset{+1}{H}_{2}\overset{+3}{C}_{2}\overset{-2}{O}_{4}

Clearly, there is no change in the oxidation states.

\overset{+2}{Mg}(\overset{-2}{O}\overset{+1}{H})_{2}+2\overset{-3}{N}\overset{+4}{H}_{4}Cl\rightarrow\overset{+2}{Mg}\overset{-1}{Cl}_{2}+2\overset{-3}{N}\overset{+1}{H}_{4}\overset{-2}{O}\overset{+1}{H}

Clearly, there is no change in the oxidation states. 

Finally , 

\overset{0}{Zn}+2\overset{+1}{Ag}\overset{+2}{C}\overset{-3}{N}_{2}\rightarrow2\overset{0}{Ag}+\overset{+2}{Zn}(\overset{+2}{C}\overset{-3}{N})_{2}

Clearly, there is a change in the oxidation status of the constituents.

\thereforeThe last reaction is redox.

The oxidation states show a change only in reaction (d).

 

 


Option 1)

NaCI+KNO_{3}\rightarrow NaNO_{3}+KCI

This option is incorrect.

Option 2)

CaC_{2}O_{4}+2HCI\rightarrow CaCI_{2}+H_{2}C_{2}O_{4}

This option is incorrect.

Option 3)

Mg(OH)_{2}+2NH_{4}CI\rightarrow MgCI_{2}+2NH_{4}OH

This option is incorrect.

Option 4)

Zn+2AgCN\rightarrow 2Ag+Zn(CN)_{2}

This option is correct.

Posted by

divya.saini

View full answer

JEE Main high-scoring chapters and topics

Study 40% syllabus and score up to 100% marks in JEE

Similar Questions

Trending Articles/News

anam-khan

BTech Admission 2025 Live: JEE Mains, SRMJEEE, MET registrations underway; MHT CET syllabus updates
anam-khan

Centre issues coaching guidelines, prohibits centres from using false claims like '100% selection'
anam-khan

BTech Admissions 2025 Live: JEE Mains, SRMJEE, VITEEE dates out; AEEE, MET registrations underway

Latest Question