It is the idea of John Newlands about the similarity of every eight elements in the periodic table.

It is the state of matter with definite mass and volume but indefinite shape.

Which of the following is an example of an element?

Napthaline balls are placed in our cabinets to avoid cockroaches. It changes from a solid phase to a gaseous phase. What process is present in this scenario?

An atom contains 34 electrons and 35 neutrons. How many protons are there?

What is the mass number of an atom with 20 electrons and 25 neutrons?

What is the atomic number of an atom with 40 neutrons and mass number of 75?

What element below can satisfy this electronic configuration: 1s2 2s2 2p6 3s2 3p2 ?

Which of the following is the correct electron configuration of carbon -6?

He found out that elements should be arranged in increasing atomic number and not mass number.