Identify the wrong statement for a long form of periodic table.
(A)- It reflects the sequence of filling the electrons in the order of energy levels K, L, M, N
(B)- It helps to predict the stable valence states of the elements
(C)- It reflects trends in physical and chemical properties of the elements
(D)- it helps to predict the relative ionicity of the bond between any two elements

Hint: The arranging of the elements with the increase in the number of electrons or atomic number in specific rows and columns, showing properties which can be predicted and compared along it.

Complete step by step answer:
In the long form of periodic table, the elements are arranged in the order of their atomic numbers such that the physical and chemical properties repeat at periodic intervals with respect to it. This is known as the Modern periodic law.
- Due to this law, the table is arranged in a manner, having 18 vertical columns called Groups and 7 horizontal rows called the Period.
- As in the group and period, we see that along a row, with increase of atomic number, electrons are placed in the same shell until they reach the inert gas configuration. Whereas, in a column, there is an increase in the order of energy level as K, L, M, N but having the same valence electrons.
- The dependence of the physical properties can be seen on the nuclear mass whereas the valence electrons decide the chemical nature of the element with respect to its group or period. Such as the electronegativity, boiling point, melting point, ionisation enthalpy etc.
- Also, in the table the elements are found to be distinguished into their metallic nature on the extreme left side and non-metallic nature on the extreme right as we move along the row. This helps in defining the nature of the bonds formed between the elements, that is, their relative ionic character. But, the stability of an oxidation state of an element, which variable oxidation states possible cannot be predicted from the table.

Thus, the wrong statement for the long form of periodic table is option (B)- It helps to predict the stable valence states of the elements.

Note: The exact position and configuration of an element can be easily determined from the table and its properties can be easily defined. This can further help in making comparisons between elements feasible.