$Average\ atomic\ mass=(\frac {\%\ of\ the\ first\ isotope}{100}\times {Mass\ of\ the\ first\ isotope})+(\frac {\%\ of\ the\ second\ isotope}{100}\times {Mass\ of\ the\ second\ isotope})$

Given that:

For first isotope:

% = 50.69 %

Mass = 78.9183 amu

For second isotope:

% = 49.31 %

Mass = 80.9163 amu

Thus,

$Average\ atomic\ mass=\frac{50.69}{100}\times {78.9183}+\frac{49.31}{100}\times {80.9163}\ amu$

$Average\ atomic\ mass=40.0036+39.8998\ amu$

Average atomic mass = 79.9034 amu

4 0

3 years ago

Based on this table, what do the group 18 elements have in common?_

Inessa05 [86]

Common thing is that their outmost shell is completely filled with the electrons. They are inert gases.

3 0

3 years ago

How many moles are in 25 g of NaCl

Olenka [21]

4.5098 moles i believe'

3 0

3 years ago