Question

Write position of following elements in periodic table i) Lanthanum (z = 57) ii) Cerium (z = 58) iii) Actinium (z = 89) iv) Thorium (z = 90)

Answer 1

Lanthanum = 6th period, 3rd group

Cerium= outside the periodic table(lanthanoides)

Actinium= 7th period, 3rd group

Thorium = outside the periodic table ( actinoides)