Which of the following are isostructural? (1) `BF_(3)`,
(2) `SO_(4)^(2-)`,
(3) `NO_(3)^(-)`
(4) `NH_(4)^(+)`
(5) `CO_(3)^(2-)`
(6) `PO_(4)^(3-)`.

Explanation

`BF_(3),NO_(3)^(-) and CO_(3)^(2-)` are isostructural (trigonal planar and all the central atoms are `sp^(2)`-hybridised) and `SO_(4)^(2-),NH_(4)^(+)` and `PO_(4)^(3-)` are isostructural (tetrahedral and all the central atoms are `sp^(3)`- hybridised).