Answer:
D. bromine
Explanation:
Highest electronegativity in the period has element closest to the *A group
K Ca Cu Br
the branch of science that deals with the identification of the substances of which matter is composed; the investigation of their properties and the ways in which they interact, combine, and change; and the use of these processes to form new substances.the branch of science that deals with the identification of the substances of which matter is composed; the investigation of their properties and the ways in which they interact, combine, and change; and the use of these processes to form new substances.
ANSWERS:
1.

⇒ 2KCl +

2.

⇒

3.

⇒

4.

⇒

5.

⇒

I have attached my work for 1-3. I would like to see if you can get 4 and 5 on your own. but, if you are struggling/copnfused please let me know in the comments! :)
Phosphorus has 16 neutrons. Phosphorous is 15 on the periodic table, which means that the atomic number (number of protons) of phosphorous is 15.
For more info: https://study.com/academy/answer/what-is-the-number-of-neutrons-in-phosphorus.html
Answer:
Beryllium
Explanation:
They are in the same group