Chemistry

Total Questions: 69

41. The mass of a particle of which of the following substances is equal to the mass of the electron, but the charge is positive? [C.P.O. S.I. 11.06.2016]

(a) Positron
(b) Neutron
(c) Protons
(d) beta particle

Correct Answer: (a) Positron

Solution:A positron is a positively charged fundamental particle whose mass and charge are equal to that of an electron. That's why it is called the 'anti-particle' of the electron. Its spin is 1/2.

42. Which of the following is included in the nucleus of an atom? [C.P.O. S.I. 5.06.2016]

(a) protons and neutrons
(b) proton and electron
(c) electron
(d) Proton

Correct Answer: (a) protons and neutrons

Solution:The particles included in the nucleus of an atom are protons and neutrons. The nucleus is the small, dense center of an atom and contains positively charged protons and neutral.
The Structure of the Atom – Introductory Chemistry

The Structure of the Atom – Introductory Chemistry

43. The number of electrons in the outermost shell of most stable or inactive atoms is- [S.S.C. Online MTS (T-I) 21.09.2017]

(a) 1
(b) 5
(c) 3
(d) 8

Correct Answer: (d) 8

Solution:If the number of electrons in the outermost shell of an atom is 8, then it is said to be in a stable or completely satisfied state. Such atoms are inert gases, which are often chemically inert, i.e. such elements do not combine with any other element quickly or easily.

44. Which of the following is a chargeless particle? [S.S.C. Online Stenographer 13.09.2017]

(a) Alpha particle
(b) Proton
(c) Electron
(d) Neutron

Correct Answer: (d) Neutron

Solution:
Alpha particles consist of two protons and two neutrons, giving them a positive charge.
Protons carry a positive charge.
Electrons carry a negative charge.
Neutrons are electrically neutral, meaning they have no charge.

45. The antiparticle of an electron is- [S.S.C. Online Graduate Level (T-I) 7.09.2016]

(a) Positron
(b) Proton
(c) Alpha particles
(d) Beta particles

Correct Answer: (a) Positron

Solution:A positron has the same mass and magnitude of charge as an electron, but its charge is positive instead of negative. When an electron and a positron meet, they can annihilate each other, releasing energy in the form of gamma rays.

46. Electrons move around the nucleus in motion __________. [S.S.C. Online CHSL (T-I) 21.01.2017]

(a) translatory
(b) spin
(c) orbital
(d) vibrational

Correct Answer: (c) orbital

Solution:These orbits are often described as electron shells or energy levels. While electrons also possess spin, their movement around the nucleus is best described as orbital motion.

47. The first electron shell which is the nearest to the nucleus never holds more than 'n' electrons, where 'n' is equal to: [S.S.C. Online Graduate Level (T-I) 6.03.2020]

(a) 4
(b) 2
(c) 6
(d) 8

Correct Answer: (b) 2

Solution:The filling of electrons in atomic orbitals occurs according to the Bohr - Bury law of 2n². For the first electron shell n = 1. Hence number of electrons in first shell = 2 (1)²= 2.

48. Cathode rays have ___________. [S.S.C. Online MTS (T-I) 17.09.2017]

(a) mass only
(b) charge only
(c) both mass and charge
(d) neither mass nor charge

Correct Answer: (c) both mass and charge

Solution:

Cathode rays have (c) both mass and charge.

Charge: Cathode rays are streams of electrons, and electrons carry a negative electrical charge. This was demonstrated by the deflection of cathode rays in electric and magnetic fields.

Mass: Electrons, although very light, do have mass. This was evidenced by experiments where cathode rays could cause a paddle wheel in their path to rotate, indicating they possess kinetic energy due to their mass and motion.

49. Which of the following is not a sublime? [S.S.C. Online Stenographer 13.09.2017]

(a) Camphor
(b) Naphthalene
(c) Alum
(d) Ammonium chloride

Correct Answer: (c) Alum

Solution:Those solid substances which directly change into vapor without coming into a liquid state or vapors directly into a solid state without coming into a liquid state are called 'sublime material'. Camphor, naphthalene, and ammonium chloride are sublime material, whereas alum is not sublime material. Hence option (c) will be the correct answer.

50. Which of the following processes converts liquid directly into its vapour form? [S.S.C. Online M.T.S. (T-I) 13.10.2021]

(a) Evaporation
(b) Sublimation
(c) Condensation
(d) Vaporisation

Correct Answer: (d) Vaporisation