Question

41. An element has three naturally occurring isotopes with the following masses and

   abundances (in parenthesis): 27.977 amu (0.9222); 28.974 amu (0.0469);

   29.974 amu (0.0310). Calculate the atomic weight of the element.

a.	28.09 amu
b.	66.94 amu
c.	86.93 amu
d.	29.98 amu

Answer 1

atomic weight of the element is obtained from the following formula

atomic weight = > atomic mass * abundance

here in the above problem the three isotopes possible data is given and they are substituted in the equation and gets the atomic weight as follows

atomic weight => (27.977 * 0.9222) + (28.974 * 0.0469) + (29.974 * 0.0310 )

atomic weight => 28.088464 => 28.09 amu

answer => a ) 28.09 amu