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An unknown element is found to have three naturally occurring isotopes with atomic masses of 35.9675 (0.337%), 37.9627 (0.063%) and 39.9624 (99.600%). Which of the following is the unknown element? A) Ar B) K C) CI D) Ca E) None of the above could be the unknown element.

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joseaaronlara

Answer:

The answer to your question is letter A, Argon

Explanation:

Isotope               Atomic mass                      Percent (%)

    1                       35.9675                              0.337

    2                      37.9627                              0.063

    3                      39.9624                            99.6

Average atomic mass = (Mass isotope 1)(percent 1) + (Mass isotope 2)(percent  

                                        2) + (Mass isotope 3)(percent 3)

Average atomic mass = (35.9675)(0.00337) + (37.9627)(0.00063) +

                                       (39.9624)(0.996)

Average atomic mass = 0.1212 + 0.0239 + 39.8025

Average atomic mass = 39.9476

                   Theoretical  Atomic mass

a) Ar                         39.95

b) K                          39.10

c) Cl                         35.45

d) Ca                       40.08