Doubt from periodic properties

solved
finding-atomic-number
elements
periodic-table
easy
pp
#1

Question 18 and 19 and explanation also

#2
  1. There are no element in which has 4 d electron. As the electronic configuration of last element of 4th period is 3d 10 4p 6 .
#3

For 19 it should be (B)120

#4

4th period elements start from potassium and end with krypton. They don’t have any 4d oribital in configuration.