How many of the following are correct statements

A. avogram is also called as atomic mass unit 
B. C-12 isotope is the reference element for a.m.u 
C. When STP is 1 Bar pressure and temperature is 273K molar volume is 22.7 L
D. When STP is 1 atm pressure and temperature is 273K molar volume is 22.4 L
E. Gram atomic mass is equal to the molar mass of atoms
F. mass number of an element cannot be fractional