Awave has a wavelength of 13 mm and a frequency of 20 hertz. what is it speed?

Which pair below describes isotopes of the same element? a) an atom with 6 protons and 8 neutrons - an atom with 8 protons and 6 neutrons b) an atom with 6 protons and 6 neutrons - an atom with 6 protons and 7 neutrons c) an atom with 8 protons and 8 neutrons - an atom with 7 protons and 8 neutrons d) an atom with 7 protons and 6 neutrons - an atom with 6 protons and 6 neutrons