The correct statements for peroxide ion $\left(\mathrm{O}_{2}^{2-}\right)$ are that it is diamagnetic and it has bond
order one. Electronic configuration of $\mathrm{O}_{2}^{2-}$ (peroxide ion) is
$\sigma \mathrm{l} s^{2}, \sigma^{*} 1 s^{2}, \sigma 2 s^{2}, \sigma^{*} 2 s^{2}, \sigma 2 p_{z}^{2},\left[\pi 2 p_{x}^{2}=\pi 2 p_{y}^{2}\right\}$
$$
\left[\pi^{\prime} 2 p_{x}^{2}=\pi^{*} 2 p_{y}^{2}\right], \sigma^{*} 2 p_{t}^{0}
$$
$\because$ Bond order $=$ No. of electrons present in bonding No. of electrons present in non - bonding
$\therefore \quad B O=\frac{10-8}{2}=\frac{2}{2}=1$
Number of unpaired electrons $=0$
$\mathrm{So}, \mathrm{O}_{2}^{2-}$ is diamagnetic in nature.