The cause of periodicity of properties is

The electronic configuration of an element $M$ is given below: $M: 1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^2 4p^6 4d^{10} 4f^2 5s^2 5p^6 5d^{10} 5f^0 6s^2$. Choose the correct information regarding the element $M$ for its period number,block and group number respectively.

The long form of the periodic table is based on:

What is the number of elements in periods $1$ to $7$ of the periodic table?

The number of elements in each of the long periods in the periodic table is

Which of the following statements is incorrect?