Determina la cantidad, en masa, de Cu(NO3)2 que podemos obtener, al tratar 25 g de Cu con un exceso de HNO3, si en la reacción obtenemos también NO2 más agua. ( masa atómicas: Cu:63,5 g/mol; N:14 g/mol; O:16 g/mol) Cu + 4 HNO3 ↔ Cu(NO3)2 + 2 NO2 + H2O

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.  

to improve her experimental investigation, dalila should add a row in which no fertilizer is used. by a having a contrasting row in which no fertilizer is used, she will have a control group that will her understand the effects of the fertilizer in the plant developments vs the development of the plant when no fertilizer is used.