If this decay has a half life of 20.60 years what mass of 72.5 g sodium-22 will remain after 15.6 years

hey your not cool]      

the number of protons in the nucleus of a given element. has slight luster and conducts electricity at high temperatures like metal.but like a nonmetal,boron is brittle and does not conduct electricity well at low temperatures. in graphite, carbon is a soft,brittle solid.it is reflective,ductile,or malleable.