Question

Which one of the following compounds is a peroxide ?
(a) KO₂
(b) BaO₂
(c) MnO₂
(d) NO₂

Answer 1

Key Idea In peroxides, the oxidation state of O is -1 and they give H2O2, with dilute acids, and have peroxide linkage.

In K02,

           +1 + (x

×

× 2)=0

           x = -1/2 (thus, it is a superoxide, not a peroxide.)

 In BaO2,

           +2 + (x 

×

×2) = 0

           x = -1

Thus, it is a peroxide. Only it gives H2O2 when reacts with dilute acids and has peroxide linkage as

                    Ba2+ [O - O]2-

                 (peroxide linkage)

 In

MnO

2

MnO2 and

NO

2

NO2, Mn and N exhibit variable oxidation states, thus, the oxidation state of O in these is - 2. Hence, these are not peroxides. Thus, it is clear, that among the given molecules only

BaO

2

BaO2 is a peroxide.

B✔✔✔✔✔

Answer 2

Answer:

Among the given compounds, Barium peroxide BaO₂ is a peroxide.

Explanation:  

• Chemical formula of peroxide is [O₂]²⁻. In which each oxygen has  -1 oxidation state.
• KO₂ : It can be written as K⁺[O₂]⁻. So each oxygen atom has -1/2  oxidation state. Therefore it is a superoxide.
• BaO₂ :  It can be written as Ba²⁺[O₂]²⁻. So each oxygen atom has -1  oxidation state. Therefore it is a peroxide.
• MnO₂ : It can be written as Mn⁴⁺[O₂]⁴⁻. So each oxygen atom has -2 oxidation state. Therefore it is an oxide.
• NO₂ : It is nitrogen dioxide. It exists in dimeric form N₂O₄.

Therefore the option b is correct.