Question

3. The elements ABCD and with atomic number given below. based on this answer the
following:
Atomic number 7
19
1) Two elements resembles in chemical properties ilnert gas neen
MA
3.
din descending onder of their atomics and videos​

Answer 1

Let us take a look at the electronic configurations of the given elements,  

A: (2, 7)

B: (2, 8, 1)  

C: (2, 8, 7)

D: (2, 8, 2)

E: (2, 8, 3)

We can see that elements A and C both have 7 valence electrons. Thus, both the elements belong to the same group.