Explain how elements are arranged on the periodic table. in other words, explain why they are not just listed in one long list, but are instead grouped into rows and columns. also, describe the placement of metals, metalloids, non-metals, and noble gases on the periodic table.

The mass of a neutron is equal to the mass of a proton plus the mass of an electron. true or false false true

Which element is the least metallic between cadmium, silver, zinc, or iron?

)benzene and toluene form nearly ideal solutions. consider an equimolar solution of benzene and toluene. at 20 °c the vapour pressures of pure benzene and toluene are 9.9 kpa and 2.9 kpa, respectively. the solution is boiled by reducing the external pressure below the vapour pressure. calculate (i) the pressure when boiling begins, (ii) the composition of each component in the vapour, and (iii) the vapour pressure when only a few drops of liquid remain. assume that the rate of vaporization is low enough for the temperature to remain constant at 20 °c.