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

Explanation

The bond length in a molecule is dependent on bond order. The higher is the bond order, smaller will be the bond length. Peroxide ion, `O_(2) ^(2-)`
`O _(2) ^(2-): K K ' ( sigma 2s)^(2) (sigam ^(**2s)^(2) (sigma 2p_(z)) ^(2) (pi 2p _(x))^(2) (pi 2 p _(y)) ^(2) (pi ^(**)2p_(s)) ^(2) (pi ^(**)2p _(y))_(2)`
Bond order `=( 10-8)/(2) =1`
Duperoxide ion O _(2) ^(-)`
`O _(2) ^(-) : KK^(**)(sigma 2s) ^(2) ( sigma ^(**)2s) ^(2) (sigma 2p_(z))^(2) ( pi 2p _(x))^(2) ( pi 2p_(y))^(2) ( pi ^(**)2p_(x)) ^(2) ( pi ^(@@)2p_(y)) ^(1)`
Bond order `= ( 10-7)/(2)=1.5`
Bond order of superoxide ion is higher than peroxide ion, hence bond length of peroxide ion is larger.