True or false: Electromagnetic waves can pass through a vacuum but mechanical waves can not.

May someone explain how to do this question?

What is the radius of the circular path ofa charged particle in a magnetic field?

When you see distant streetlights through smog, they look dimmer and redder than they do normally. but when you see the same streetlights through fog or falling snow, they look dimmer but not redder. use your knowledge of the interstellar medium to discuss the relative sizes of the particles in smog, fog, and snowstorms compared to the wavelength of light.