Which were the first heavy elements to be created in a laboratory, and where and when were they created?

Determine the wavelength of the light absorbed when an electron in a hydrogen atom makes a transition from an orbital in the n=3 level to an orbital in the n=7 level.

Answer asap : ( a. how does mucus prevent the entry of pathogens? b. describe two ways white blood cells protect us from pathogens.

How will the volume of a gas be affected if the pressure is tripled, but the temperature remains the same?