The Development of the Periodic Table

Dissimilar elements are placed in the same group in Mendeleev's periodic table.

Some elements which are chemically similar are placed in different groups.

Noble gases were placed in Mendeleev’s periodic table without disturbing the positions of other elements.

The Newlands' Law of Octaves was applicable only for elements up to magnesium.

According to Dobereiner, the arithmetic mean of the atomic masses of the second and third element in a triad is approximately equal to the atomic mass of the first element in that triad.

The total number of elements present in the modern periodic table is $116$.

Why the Mendeleev's periodic table was better than Meyer's table?

The atomic masses of $\mathrm{L}\mathrm{i}$ and $\mathrm{K}$ are $7$ and $\mathrm{39,}$ respectively. According to law of triads the atomic mass of $\mathrm{N}\mathrm{a}$ will be

How many elements are known till the end of $2020$.

By $1865$, how many elements had been identified?

Mendeleev left the gap under aluminium and a gap under silicon having atomic weights $68$ and $72$ respectively. These elements respectively are 

In Mendeleev's periodic table, iodine with lower atomic weight than that of tellurium was placed along with 

Which of the following statements is incorrect?

Which of the following statements is incorrect?

According to Mendeleef's periodic law,the elements were arranged in the Periodic Table in the order of 

What type of oxide would Eka-aluminium form?

Eka-aluminium and Eka-silicon are known as

For which of the pairs, Newland octave rule is not applicable?

Which of the following set of elements obeys Newland's octave rule?

The law of triads is not applicable on