Aluminum would be the answer
Usually, elements with more similar properties share the same column on the periodic table.
Therefore, if you look at the periodic table, you can see that Oxygen, Sulfur, and Selenium all share the same column. Therefore, they all have similar properties
Answer: #3 ( O, S, Se )
Hope this helped!!! :D
It has 49 electrons as well. The amount of protons and electrons are equal.
Yes , it does become massive and it also becomes heavier.