Oxygen and tin 4 chloride react form chlorine and tin 3 oxide

Asingle atom of an element has 21 neutrons, 20 electrons, and 20 protons. which element is it? ok o z

Can someone me with questions 15 to 17 plz.

)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.