What was concluded about the structure of the atom as the result of the gold foil experiment?
(1) a positively charged nucleus is surrounded by positively charged particles.
(2) a positively charged nucleus is surrounded by mostly empty space.
(3) a negatively charged nucleus is surrounded by positively charged particles.
(4) a negatively charged nucleus is surrounded by mostly empty space.

Ican determine the molar mass of an element by looking on the under the atomic mass for the element. for example the molar mass of phosphorus is 30.974 grams/mole. avogadro’s number tells me the amount of representative particles in 1 mole of any substance. this means 12.011 gram sample of carbon and a 32.0 gram sample of sulfur have the same number of atoms.

)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.

Estimate the molar mass of the gas that effuses at 1.6 times the effusion rate of carbon dioxide.