Discuss the position of lanthanides in the periodic table.

Discuss the position of hydrogen in the periodic table is not justified.

Justify the position of Hydrogen in the periodic table.

Explain the position of d-block elements in the periodic table.

What will be the position of the daughter nucleus in the periodic table, when beta^(+) and beta^(-) decays take place? Give an example under each.

The 18th group of elements in the periodic table is called

Transition metals lie in the periodic table between groups

The first element in the periodic table is_____.

(a) Which two criteria did Mendeleev use to classify the elements in his periodic table ? (b) State Mendeleev's periodic law. (c) Why is it not possible to give a fixed position to hydrogen in Mendeleev's periodic table ?

State two main properties of elements on which Mendeleev's periodic classification was based. Why position of hydrogen is not fixed in his periodic table ?