joy0608 joy0608 25-10-2020 Chemistry contestada An unknown element sample has 3 isotopes present. The first isotope has a mass of 23.98 amu and is 78.7% abundant. The second has a mass of 24.98 amu and abundance of 10.13%. The last isotope has a mass of 25.93 amu and an abundance of 11.17%.