A chlorine Cl and bromine Br atom are adsorbed on a small patch of surface (see sketch at right). This patch is known to contain 49 possible adsorption sites. The Cl and bromine Br atoms have enough energy to move from site to site, so they could be on any two of them. Suppose the Br atom desorbs from the surface and drifts away. Calculate the change in entropy. Round your answer to 2 significant digits, and be sure it has the correct unit symbol.

It is a mixture. simply put, a compound must be pure, that is, of only one chemical structure and composition. a mixture is made of different chemical substances (i.e. elements, molecules, compounds) that are not chemically bonded to each other, but instead physically grouped together, as in the case of gasoline (a homogeneous solution).

Ithink about 50 % of an original isotope's number of atoms remain

Vander waals forces are inter molecular bonds that exist within molecules of the same substance. a water molecule is made up of oxygen and hydrogen atoms which share electrons between each other. the vander waals forces are forces that exist between multitude of different  molecules of water. dipole dipole forces is the type of vander waals force that exist in water. the oxygen atom which is more electronegative pulls the shared electron closer to itself thus generating a partial negative charge while the hydrogen acquire a partial positive charge. these two different charges causes attraction to occur in water molecules.