Standard temperature and pressure (STP) means a temperature of 0°c and a pressure of 1 atmosphere (atm). The molar gas volume is used to convert between the number of moles of a gas and the volume of the gas at STP. One mole of a gas occupies a volume of 22400 cm³ or 22.4 liters at STP according to the molar gas volume.
The potassium chloride is KCl. The gram formula mass of KCl is 39+35.5=74.5 g/mol which means 74.5 g per mole of KCl. So the mass of KCl is 6.90*74.5=514 g.
Elements cannot be broken down in this fashion.
Compounds, homogeneous mixtures, and heterogeneous mixtures can be broken down or separated with chemical processes, or in some cases, just by manual separation.
