Which of the following statements is/are incorrect -
A. Number of atoms present in 80 amu Ca are `2 N_A`
B. Volume occupied by 2g-atom oxygen at 1 atm pressure and 273 K temperature is 44.8 L
C. 9.8 g of `H_2SO_4` has 3.2 g of S-atom
D. `H_2`(g) is an elemental form as well as a molecule of hydrogen.
