Question

14. The electron configuration 1s22s22p63s23p6 applies to all of the following species except: A) Br B) 92- C) 02- D) CI E) Ca2+

Answer 1

In 1s22s22p63s23p6, number of electrons = 18

Atomic number of Br = 35

So, number of electrons in Br = 35

Since charge on Br is -1

Number of electrons in Br- = 36

Atomic number of S = 16

So, number of electrons in S = 16

Since charge on S is -2

Number of electrons in S2- = 18

Atomic number of O = 8

So, number of electrons in O = 8

Since charge on O is -2

Number of electrons in O2- = 10

Atomic number of Cl = 17

So, number of electrons in Cl = 17

Since charge on Cl is -1

Number of electrons in Cl- = 18

Atomic number of Ca = 20

So, number of electrons in Ca = 20

Since charge on Ca is +2

Number of electrons in Ca2+ = 18

Only Br- do not have 18 electrons

Answer: A