Magnesium has three stable isotopes: 24Mg, 25Mg, 26Mg. The relative abundance of 24Mg is 79%.

What are the relative abundances of 25Mg and 26Mg?

Mg 24 = 78.90%

Mg 25 = 11.70%
Mg 26 = 9.400%

If you want to do this exactly, you will need to know the masses of the isotopes; i.e., they are not exactly 25, 26, and 24. The problem is done this way.

Let x = abundance 25
Then 1.00-0.79-x =0. 21-x = abundance 26.
(0.79*24) + (x*25) + (0.21-x)*26 = 24.3
You will need to substitute the actual masses for 24, 25, & 26 in the above as well as the actual mass of the 24.3 total. Post your work if you get stuck.

State three limitations of Bohr's model of atom

Full calculations of my questions

To determine the relative abundances of 25Mg and 26Mg, we need to subtract the relative abundance of 24Mg from 100% since the total relative abundance of all stable isotopes should add up to 100%.

Given that the relative abundance of 24Mg is 79%, we subtract it from 100%:
100% - 79% = 21%

Therefore, the relative abundance of 25Mg is 21% and the relative abundance of 26Mg is also 21%.

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