What is the molarity of 10.0 g of kcl in 0.500 l of solution

Molarity is defined as number of moles of the solute in 1 liter of solution.

Molarity = Moles of solute (mol) / Volume of the solution (L)

moles of KCl = mass (g) / molar mass (g/mol)
                      = 10.0 g / 74.5 g/mol
                      = 0.134 mol

Hence molarity = 0.134 mol / 0.500 L
                         = 0.268 mol/L

All the elements are arranged by melting points on the periodic table. in row they go from metals to gasses. in the row from sodium to argon, sodium is more reactive than the one on its right, magnesium.