Which of the following statement about the sulphate of alkali metal is correct?
(a) Expect all sulphate of other alkali metals are soluble in water
(b) All sulphate salts of alkali metals except lithium sulphate forms alum.
(c) All sulphate salts of alkali metals except lithiumsulphate do not decompose at high temperature
(d) All of the above
(d) All are facts.