Why do elements within a group have similar chemical properties

In what direction does the medium move relative to the direction of the wave? explain.

Alfred pushes on a heavy box, but cannot move it. the box has a lot of inertia motion friction gravity

Amichelson interferometer operating at a 600 nm wavelength has a 3.02-cm-long glass cell in one arm. to begin, the air is pumped out of the cell and mirror m2 is adjusted to produce a bright spot at the center of the interference pattern. then a valve is opened and air is slowly admitted into the cell. the index of refraction of air at 1.00 atm pressure is 1.00028.how many bright-dark-bright fringe shifts are observed as the cell fills with air?