Answer:
atomic number of Be =4
electronic configuration :1s²2s²
but for Be2+ atomic number = 4-2 =2
electronic configuration : 1s²
The answer is 3.
Explanation:
It’s the last number and it can’t be 9 because then it would be 48.9 and no 3.
Answer:
the first one which is A
Explanation:
the burning of fossil fuels causes both air pollution and water pollution
The sun gives off light energy to help plants photosynthesize and make food
