What do you mean by isoelectronic species? Name species that will be isoelectronic with each of the given atoms or ions
(1) `F^(-)`
(2) `Ar`.

Explanation

Isoelectronic ions are ions of different elements which have the same number of elements but different magnitude of nuclear charge.
(1). There are (9+1) or 10 electrons in `F^(-)` isoelectronic species of `F^(-)` are nitride `(N^(3-))` ion [7+3], oxide `(O^(2-))` ion [8+2] neon `(Ne)` atom [10], sodium `(Na^(+))` ion `[11-1]`, magnesium `(Mg^(2+))` ion [12-2], aluminium `(Al^(3+))` ion [13-3].
There are 18 electgrons in Ar. isoelectronic species of Ar are phosphide `(P^(3-))` ion [13+3], sulphide `(S^(2-))` ion [16+2]. chloride `(Cl^(-))` ion [17+1], potassium `(K^(+))` ion [19-1], calcium `(Ca^(2+))` ion [20-2].