what is the reaction between tetraoxosulphate(vi) and calcium hydroxide

2 answers

aren't you missing a metal to go with that tetraoxosulphate(vi) ion?

in any case, surely a few seconds with an online search will provide you with what you need.
tetraoxosulphate(vi)
I think the missing word here is "acid". In the parlance used by these posters, this means H2SO4. Then
H2SO4 + Ca(OH)2 ==> CaSO4 + 2H2O.
I rue the day that the IUPAC decided to get the STOCK system embedded in the naming of compounds. Used correctly, the Stock system properly names compounds so that CuS and Cu2S names are not confused; however, I think the novice has tried to "meld" two naming systems and came up with this tetraoxo stuff. I can't prove that but I just do not believe that tetraoxosulfate(VI) is a correct IUPAC name for H2SO4.