Answer: 63.26%
Explanation:
If we let the abundance of the first isotope be x, then:

Which is equal to <u>63.26%</u>
The answer would be 0.55 moles! good luck!
The correct option is STRONTIUM.
Strontium is a group 2 element, that means it has two electrons in its outermost shell. This element will prefer to lose these two electrons in its outermost shell in order to attain the octet form, therefore, it will form electrovalent bond with non metals which it can donate two electrons to.
Mixture......................