Answer:
Various limitations of Mendeleev's periodic table are:-
Position of hydrogen - he couldn't assign a correct position to hydrogen as it showed properties of both alkali and halogens .
Position of isotopes - he considered that the properties of elements are a function of their atomic masses. Hence isotopes of a same element couldn't be placed.
In the d-block , elements with lower atomic number were placed before higher atomic number.
Explanation:
option A.
The number of valence electrons of an element can be determined by the periodic table group (vertical column) in which the element is categorized
an atom because its the smallest thing in the entire world and in all orgnaisms
Answer: Option (D) is the correct answer.
Explanation:
A polymer is a large molecule which contains repeating units.
A polymer forms long chain of atoms which are not necessarily arranged in a ring structure. There are not only double bonds between all the carbon atoms, as there can be single bonds or triple bonds between the atoms of a polymer.
A polymer does not contain many different type of molecules as there are many repeating units and not many molecules in a polymer.
A polymer is made of large molecules with repeating units.
Thus, we can conclude that option (D) is the correct answer.
