Ions of the elements oxygen (o), sulfur (s), and selenium (se) usually have charges of 2-. ions of the elements fluorine (f), chlorine (cl), and bromine (br) usually have charges of 1-.

True

Explanation:

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As long as the group VIA elements have 6 valence electrons (electrons at the outermost shell) they just need two electrons to attain the octate, it means that the resulting charge must be -2. In such a way, since VIIA elements have 7 valence electrons, they just need one electron to attain the octate, it means that the resulting charge must be -1.

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The Elements in the same group share certain properties, and each group has unique properties.

Explanation: Study island

it is a good conductor

explanation:

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%