Answer
(a) $TeO_4^-$
(b) $AsO_3^{-}$
(c) $SeO_4^{2-}$
(d) $ClO_3^-$
Work Step by Step
For some of the oxoanions, we may have to refer to the internet for their formulas and charges.
(a) Potassium (K) has an oxidation number of $1+$ because it has a single electron in its outermost energy level that it can donate to another atom or ion. Tellurite has a formula of $TeO_4^-$. Therefore, the compound formed between these two substances is $KTeO_4$.
(b) Sodium (Na) has an oxidation number of $1+$ because it has a single electron in its outermost energy level that it can donate to another atom or ion. Arsenate has a formula of $AsO_3^{-}$. Therefore, the compound formed between these two substances is $NaAsO_3$.
(c) Calcium (Ca) has an oxidation number of $2+$ because it has two electrons in its outermost energy level that it can donate to another atom or ion. Selenite has a formula of $SeO_4^{2-}$. Therefore, the compound formed between these two substances is $CaSeO_4$.
(d) Potassium (K) has an oxidation number of $1+$ because it has a single electron in its outermost energy level that it can donate to another atom or ion. Chlorate has a formula of $ClO_3^-$. Therefore, the compound formed between these two substances is $KClO_3$.
