Ramnik is a student of class 9. One day he was studying a chapter of chemistry in the class alongwith other students. The teacher, Mr. Bhagi, told the students that the scientists James Chadwick J.J. Thomson and E. Goldstein had discovered three subatomic particles P, Q and R, respectively. He gave the characteristics of all these particles, their locations and arrangements in the atom. Mr. Bhagi also described the contributions of scientists Ernest Rutherford and Neils Bohr in this regard. After completing the discussion on this chapter, Mr. Bhagi asked Ramnik to answer the following question :
(a) What is the name of particle P ? What is the nature of charge on it ? State its location in tha atom
(b) What is the name of particle Q ? What is the nature of charge on it ? State its location in the atom
(c) What is the name of particle R ? What is the nature of charge on it ? State its location in the atom
(d) (i) Which of the particles P,Q and R is not present in an ordinary hydrogen atom
(ii) Which of the particles P,Q and R is not present in an alpha particle ?
(e) What is the total number of P and R particles present in one atom of an element known as ?
. (f) The number of particles Q in one neutral atom of an element is nineteen. How are these particles arranged in various energy levels in the atoms ?
(g) What values are displayed by Ramnik in this episode ?

Explanation

(a) James Chadwick discovered the subatomic particle called 'neutron'. So, the particle P is neutron. Neutron has no charge, it is electrocally neutral. Neutron is located inside the nucleus of an atom
(b) J.J. Thomson discovered the subatomic particle called electron. So, the particle Q is electron. Electron has negative charge. The relative charge of an electron is, -1 (minus one). Electron is located outside the nucleus in an atom
(c) E. Goldstein discovered the subatomic particle called 'proton'. So, the particle R is proton. Proton has positive charge. The relative charge of a proton is +1 (plus one). Proton occurs inside the nucleus of an atom.
(d) Particle P (neutron) is not present in an ordinary hydrogen atom
(ii) Particle Q (electron) is not present in an alpha particle.
(e) The total number of particles P (neutrons) and R (protons) in one atom of an element is called its mass number
(f) The number of particle Q (or electrons) in one neutral atom of the element is 19. These 19 electrons can be arranged in four energy levels or shells as `underset("2, 8, 8, 1")("K L M N")`
(g) The various values displayed by Ramnik in this episode are (i) Knowledge of the structure of atom, and
(ii) Ability to use this knowledge in solving problems.