Which of the two peroxide ion or superoxide ion has larger bond length ?

Explanation

The bond length of a molecule is related to its bond order. The larger the bond order, the smaller will be the bond length.
`O_(2)^(-):KK(sigma2s)^(2)(sigma^(**)2s)^(2)(sigma2p_(z))^(2)(pi2p_(x))^(2)(pi2p_(y))^(2)(pi^(**)2p_(x))^(2)(pi^(**)2p_(y))^(1)`
`"Bond order "=(8-5)/(2)=1(1)/(2)`
Peroxide ion, `O_(2)^(2-)`:
`O_(2)^(2-):KK(sigma2s)^(2)(sigma^(**)2s)^(2)(sigma2p_(z))^(2)(pi2p_(x))^(2)(pi2p_(y))^(2)(pi^(**)2p_(x))^(2)(pi^(**)2p_(y))^(2)`
`"Bond order "=(8-6)/(2)=1`
Now, superoxide ion `(O_(2)^(-))` has larger bond order than perioxide ion `(O_(2)^(2-))`, therefore, bond length of peroxide ion will be larger.