Question

PLEASE HELP!!!!!!!!!

Answer 1

The average atomic mass of the imaginary element : 47.255 amu

Further explanation  

The elements in nature have several types of isotopes  

Isotopes are elements that have the same Atomic Number (Proton)  

Atomic mass is the average atomic mass of all its isotopes  

Mass atom X = mass isotope 1 . % + mass isotope 2.% ..

isotope E-47 47.011 amu, 87.34%

isotope E-48 48.008 amu, 6.895

isotope E-49 50.009 amu, 5.77%

The average atomic mass :

$\tt avg~mass=0.8734\times 47.011+0.06895\times 48.008+0.0577\times 50.009\\\\avg~mass=41.059+3.310+2.886\\\\avg~mass=47.255~amu$