The periods and groups on the periodic table are numbered. For example element Francium (Fr) is in period 1, group Fr is very reactive metal and t
does react violently with water. Which of the following elements is likely
properties that are similar to those of Fr?

H+ + cn– + li+ + oh– mc001-4.jpg li+ + cn– + h2o

The main types of electromagnetic radiation. radio  waves have  the lowest frequencies  and  longest  wavelengths, while gamma  waves have highest frequencies  and shortest wavelengths. the wavelengths vary across the electromagnetic spectrum from about 10–15 m to more than 104 m.hope it !