Respuesta :

Edufirst
HNO3 molar mass = 1 + 14 +3*16 = 63 g/mol

# of moles = mass / molar mass - 25.0 g / 63 g = 0.3968 moles

# of atoms = # of moles * Avogadro number = 0.3968 mol * 6.022 *10^23 atoms/mol = 2.39 * 10^23 atoms