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 .

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-