Where do the electrons come from that produce heat and light in a light bulb?

According to the vsepr theory what is the shape of a molecule that has a central atom valence three other items with no lone pairs of electrons

Under which circumstances are kp and kc equal for the reaction aa(g)+bb(g)⇌cc(g)+dd(g)?

Which example is a mechanical wave?     a.microwave    b.radio wave    c.water wave    d.ultraviolet light