The formula of an iodate of lanthanum is la(io3)3. what is the formula of the sulfate of lanthanum with the same oxidation number

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Explanation:-

For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.  

Here lanthanum is having an oxidation state of +3 called as cation and iodate is a polyatomic anion with oxidation state of -1. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral .

For formation of sulfate of lanthanum, lanthanum will have same oxidation state of +3 called as cation and sulphate is a polyatomic anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral .