What is the atomic mass of bromine, given the atomic masses and percent abundance of the two isotopes are 78.92 amu (50.7%) and 80.92 amu (49.3%)? Select one:
a. 79.9 amu
b. 78.9 amu
c. 80.9 amu
d. 35 amu

79.9 amu

Explanation:

Given data:

Atomic mass of bromine = ?

Percent abundance of 1st isotope = 50.7%

Atomic mass of 1st isotope = 78.92 amu

Percent abundance of 2nd isotope = 49.3%

Atomic mass of 2nd isotope =80.92 amu

Solution:

Average atomic mass  = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass)  / 100

Average atomic mass = (50.7×78.92)+(49.3×80.92) /100

Average atomic mass =  4001.24 + 3989.36 / 100

Average atomic mass = 7990.6 / 100

Average atomic mass = 79.9 amu.

plants need sunlight, water, and carbon dioxide to make food. plants use the raw materials of water, nutrients they absorb from soil, and carbon dioxide to make sugars the plant can use. energy from the sun and chlorophyll are also needed.