Q1: All the atoms of the world comprise of electrons, proton & neutron except that of __________ atom in which neutron is absent.

ANS:B - hydrogen

Hydrogen is the simplest and lightest element in the periodic table. A hydrogen atom consists of one proton in its nucleus and one electron orbiting the nucleus. Here's a breakdown of the components of a hydrogen atom:

1. Proton: The nucleus of a hydrogen atom contains one proton. Protons are positively charged subatomic particles found in the nucleus of atoms. The proton contributes to the positive charge of the nucleus and determines the element's identity.
2. Electron: Orbiting the nucleus of a hydrogen atom is one electron. Electrons are negatively charged subatomic particles that occupy regions of space called orbitals around the nucleus. They balance the positive charge of the protons, making the atom electrically neutral overall.
3. Neutron: The nucleus of a normal hydrogen atom (known as protium) does not contain any neutrons. Neutrons are neutral subatomic particles found in the nucleus of most atoms, but in the case of hydrogen, there are none. However, isotopes of hydrogen, such as deuterium and tritium, contain one and two neutrons in their nuclei, respectively. These isotopes are less common and are typically found in small quantities in nature.