Classification ...

Consider the isoelectronic species, Na⁺, Mg²⁺, F^- and O^2-. The correct order of increasing length their radii is.

Mendeleev 'Periodic Law' states that

Mendeleev arranged elements in a periodic table in order of their increasing atomic weights in such a way that the elements with similar properties occupies

Correct option to complete the following statement  is :
"Mendeleeve's classification of element is based upon similarites in properties of different elements with increasing order of their atomic weights .
In cases where  dissimarites in properties of an element appeared he placed the elements with similar ......... together".

Mendeleev proposed that some of the elements were still undiscovered and, therefore, left several gaps in the table. He left the gap under aluminium and a gap under silicon, and called these elements Eka-Aluminium and Eka-Silicon. These were later discovered and named

Complete the statement with suitable  word /(s)
Modern Periodic Law is stated as:
"Physical and chemical properties of different elements are periodic functions  of their ......... ?

It is now recognized that the ‘Modern Periodic Law’ is essentially the consequence of 

In the modern periodic table

According to the recommendation of International Union of Pure and Applied Chemistry (IUPAC), the groups in the modern periodic table are numbered from

Choose one of the following in the order of increasing radii: