Correct Answer - B
`Na^(+) gt Li^(+) gt Mg^(+2) gt Be^(+2)`
`116 p m gt 90 p m gt 86 gt`
Ionic size increases down the group and decreases in period from left to right.
`CaCO_(3) overset(Delta)(rarr) underset("Basic")(CaO)+underset("Acidic")(CO_(2))`
`NH_(4)NO_(3) overset(Delta)(rarr) underset("Neutral oxide")(N_(2)O+H_(2)O)`