1.2.Which of the following statements concerning carbamide peroxide is false?

A、 it breaks down to approximately 35.-36.% hydrogen peroxide.
B、 it is used for vital nightguard bleaching.
C、 it irritates skin and mucosa.
D、 it is also known as sodium perborate.
E、 it is available commercially and relatively frequently used in the concentration of 1.0.-1.5.%.