7. Iron has 2 isotopes, Fe - 55 with an abundance of 15.35% and Fe - 56 with an abundance of 84.65%. What is the average atomic mass of iron?

Average atomic mass  = 55.85 amu

Explanation:

Given data:

Abundance of Fe-55 = 15.35%

Abundance of Fe-56 = 84.65%

Average atomic mass = ?

Solution:

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

Average atomic mass = (15.35×55)+(84.65×56) /100

Average atomic mass =  844.25 + 4740.4/ 100

Average atomic mass = 5584.65 / 100

Average atomic mass  = 55.85 amu.

weight of any object is given by

w = m*g

where m is mass of the object and g is the acceleration due to gravity.

for earth the value of g is 9.8 m/s^2 so

w=117.6 n m=12 g=?

117.6=12g => g=9.8 m/s^2

which is the force of gravity on earth.