501.In Gypsum bonded investment,composition of alpha hemihydrate is

a.60-65%
b.30-35%
c.5-10%
d.85-90%

Ans-b.30-35%
Explanation-Composition of gypsum bonded investment is 
Silica-60-65%
Alpha hemihydrate-30-35%
Modifiers-5%