Barium forms only the +2 state, whereas Mn, Pb and Sn have well-known +4 states. Among BaO2, MnO2, PbO2 and SnO2, which compound must contain the peroxide ion, and what is its name?

JEE Advanced levelSingle correct optionDifficulty 3 of 3bn090

Barium forms only the $+ 2$ state, whereas Mn, Pb and Sn have well-known $+ 4$ states. Among $BaO X_{2}$ , $MnO X_{2}$ , $PbO X_{2}$ and $SnO X_{2}$ , which compound must contain the peroxide ion, and what is its name?

For

BaO X_{2}

with Ba fixed at

+ 2

, the two O must total

- 2

, so each is

- 1

: the

O X_{2} X^{2 -}

peroxide ion, barium peroxide. The other three have a metal at

+ 4

with ordinary

O X^{2 -}

: oxides.