An element consists of two isotopes. the abundance of one isotope is 60.40% and its atomic mass is 68.9257 u. the atomic mass of the second isotope is 70.9249 u. what is the average atomic mass of the element? *

69.7173 u

Explanation:

The abundance of the first isotope is =60.40%

So the abundance of the second isotope =100%-60.40%=39.6%

Atomic mass of first isotope = 68.9257

So the average atomic mass of the first isotope =68.9257×0.6040=41.6311 u

Atomic mass of the second isotope =70.9249 u

So average atomic mass of second isotope =70.9249×0.396=28.086

Now the average atomic mass =41.6311+28.086=69.7173 u

average atomic mass is 69.7173 u

Explanation:

atomic mass m1 = 68.9257 u

atomic mass m2 = 70.9249 u

abundance one isotope = 60.40%  

to find out

average atomic mass

solution

we know here average atomic mass formula that is

average atomic mass = sum of ( abundance  × atomic mass )

from table we know Ga is 69.72  so abundance is 39.6

so

atomic mass = ( abundance 1 × m1 ) + ( abundance 2 × m2 ) /100

atomic mass = ( 60.40 × 68.9257 ) + ( 39.6  × 70.9249 ) /100

atomic mass = 69.7173

so average atomic mass is 69.7173 u

depends on what you mean by "group." for order, it would be coleoptera (beetles). for class, it would be insecta (insects). for phylum, it would be the arthropoda (animals with jointed exoskeletons).

explanation:

conduction, convection, radiation