State the relative charge and relative mass of a proton, neutron and electron. explain relationship between two isotopes of same element. explain why these isotopes have identical chemical properties

The bond energy for the van der waals bond between two helium atoms is 7.9×10−4ev. assuming that the average kinetic energy of a helium atom is (3/2)kbt, at what temperature is the average kinetic energy equal to the bond energy between two helium atoms

Who discovered a pattern to the elements in 1869?

The density of benzene at 15 °c is 0.8787 g/ml. calculate the mass of 0.1500 l of benzene at this temperature. enter your answer in terms of grams