you have 100 mL of 7M solution of PbNO3. if you need a 3M solution, how much water should you add to the original solution?

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante

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.