Question

What is the position of an element in the periodic table if its electron configuration is 1s2 2s2 2p6 3s2 3p5? It's a group 5A element. It's a group 6A element. It's a group 3A element. It's a group 7A element.

Answer 1

If you look at the configuration, you can see that there are less than 18 electrons (count the last numbers).  In fact, there is one less than 18: 17.  Because 18 is Argon, a noble gas, you can see that you have an element from the 17th group, or Group 7A.