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.
Answer:
CH4 + 2O2 → CO2 + 2H2O
Explanation:
This is all i could come up with im sorry.
Answer:
I believe it is 3 and 4. I really hope it is but i am positive :)
Answer:
ITS THE LAST ONE AND THE SECOND ONE
Explanation:
It's classified as an acid