Answer:
30, 50
Explanation:
Hello,
In this since an element's atomic number is equal to the number of protons in its atom, we can infer that selenium's atomic number is 30. Moreover, due to the fact the the neutrons are equal to the atomic mass minus the atomic number or the number of protons, by knowing the number of neutrons we compute the atomic as follows:

Thus, answer is 30, 50.
Best regards.
675 nanograms is equivalent to 6.75 × 10-⁴ milligrams.
<h3>How to convert nanograms to milligrams?</h3>
Nanograms is a unit of mass equal to 0.000000001 grams and has a symbol of ng.
On the other hand, milligrams is another unit of mass equal to 0.001grams and has a symbol of mg.
Nanograms and milligrams are both units of mass and can be inter-convertible as follows:
1 nanogram = 1 × 10-⁶ milligram
According to this question, 675 nanograms is equivalent to 675 × 10-⁶ milligrams.
Therefore, 675 nanograms is equivalent to 6.75 × 10-⁴ milligrams.
Learn more about milligrams at: brainly.com/question/20320382
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I always thought it was a mixture but can also be a compound
Explanation: <em>The hypothesis is a prediction, but it involves more than a guess. Most of the time, the hypothesis begins with a question which is then explored through background research. It is only at this point that researchers begin to develop a testable hypothesis.</em>
(Unless you are creating an exploratory study, your hypothesis should always explain what you expect to happen)