What acts as the binder in a phosphate-bonded investment material?

Show Answers

Magnesium oxide combined with phosphateMagnesium oxide mixed with phosphoric acidMagnesium oxide together with monoammonium phosphateMagnesium oxide and orthophosphoric acid

Explanation

In phosphate-bonded investments, the binder is formed by the reaction of magnesium oxide with monoammonium phosphate, which provides the necessary bonding properties. Other combinations listed do not serve as the binder in this context.