the mass number of atomic number of element X are.
An element X decays, first by positron emission and then two α-particles are emitted in successive radioactive decay. If the product nucleus has a mass number 229 and atomic number 89, the mass number of atomic number of element X are.
05
Jun
An element X decays, first by positron emission and then two α-particles are emitted in successive radioactive decay. If the product nucleus has a mass number 229 and atomic number 89, the mass number of atomic number of element X are. An element X decays first by positron emission and then two α-particles are emitted [...]