Question 1

Who proposed the Law of Triads?

Accepted Answer

Johann Wolfgang Dobereiner proposed the Law of Triads in the year 1817. He arranged elements with similar properties into groups of three, known as triads.

Question 2

According to Newlands' Law of Octaves, the properties of the eighth element are similar to those of the:

Accepted Answer

According to Newlands' Law of Octaves, when elements are arranged in increasing order of atomic masses, the properties of every eighth element are similar to the first element, resembling the musical notes.

Question 3

Mendeleev's periodic table was based on which fundamental property of elements?

Accepted Answer

Mendeleev's periodic table was based on atomic mass. He stated that the properties of elements are a periodic function of their atomic masses.

Question 4

Who discovered the modern periodic law based on atomic number?

Accepted Answer

Henry Moseley discovered the modern periodic law in 1913, showing that atomic number is a more fundamental property of an element than its atomic mass.

Question 5

How many groups are present in the Modern Periodic Table?

Accepted Answer

There are 18 vertical columns, known as groups, in the Modern Periodic Table.

Periodic Classification of Elements — CBSE Class 10 Science Important Questions & Revision Notes