A certain enriched sample of uranium was found to have the average atomic mass equal to 237.39 u. Assuming that it contains only two isotopes, 235U and 238U, find the abundance (in %) of 235U in that sample. The isotopic masses of 235U and 238U are 235.0439 u and 238.0508 u, respectively.

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.