Tag: mendeleev's periodic law and its limitations

In Mendeleev's periodic table, gaps were left for the elements to be discovered later. Which of the following elements found a place in the periodic table later?

The elements which have taken the place of Eka aluminium is :

Which group of elements could be placed in Mendeleev's Periodic Table without disturbing the original order?

Mendeleev classified elements in:

The elements whose atomic weight was corrected by Mendeleev are _______

Most transition metals from multiple cations, that is, they have more than one possible amount of positive charge. Virtually all of the transition metals form dipositive $(2+)$ cations, along with one or more other forms. For example, titanium forms $Ti^{2+}$ ad $Ti^{4+}$, and cobalt forms $Co^{2+}$ and $Co^{3+}$.
The principal exceptions to this predominance of cations with a $2^{+}$ charge are scandium and yttrium, which form only tripositive cations. $Sc^{3+}$ and $Y^{3+}$, and copper and silver, which form cations with a single positive charge. $Cu^{+}$ and $Ag^{+}$.
[While copper also forms dipositive $Cu^{2+}$, silver exhibits the single positive state essentially exclusively.]
Which of the following offers a POSSIBLE explanation for the existence of $Cu^{+}$ and $Ag^{+}$?

How many elements were known when Mendeleev presented the periodic table?

Mark the group which has maximum number of element in Mendeleev's periodic table:

Eka-aluminum and Eka-silicon are known as:

The Mendeleev's periodic table consists of groups: