Answer:
In first shell 2 electrons are present and 7 electrons are present in last shell
Explanation:

If the half-life of a sample of a radioactive substance is 30 seconds, how much would be left after 60 seconds? <span>
A. one-fourth</span>
Answer:
I think probably diet because the type of food you put in your body (if it has high calorie or sodium) can severley affect your overall health and therefore affect your bpm(beats per minute)
Explanation:
It’s charge was neutral due to the equal number of protons and electrons. when it becomes an ion it loses 3 electrons leaving behind only 10. the answer is 10. the equation is +13 +(-10)=+3