Why do the names of some ionic compounds include the charge of the metal ion while others do not?

The correct answer is because there are polyvalent metals.

Explanation:

Most transition metals can form cations with various loads. That is why block d of the periodic table is marked as "variable load". For example, iron is polyvalent, which means "many values", i.e. it can form cations with different loads. For polyvalent metals, we must specify the magnitude of the ion charge. In the case of anions most of the time it is not necessary to specify the magnitude of the charge of the anion.

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the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.