TRB BT Assistant - Atomic Structure and Periodic Classification Online Test (MCQ Quiz)

1. Who is credited with the discovery of the electron?

A) Ernest Rutherford B) J.J. Thomson C) John Dalton D) Niels Bohr

2. What is the atomic number of an element?

A) The number of neutrons in the nucleus B) The total number of protons and neutrons in the nucleus C) The number of protons in the nucleus D) The number of electrons in the outermost shell

3. Which subatomic particle carries a positive charge?

A) Electron B) Neutron C) Proton D) Photon

4. What is the mass number of an atom?

A) The sum of protons and neutrons B) The number of protons only C) The number of neutrons only D) The number of electrons only

5. Atoms of the same element that have different numbers of neutrons are called:

A) Isotopes B) Isomers C) Ions D) Allotropes

6. Which model of the atom proposed that electrons orbit the nucleus in specific energy levels?

A) Dalton's Model B) Thomson's Plum Pudding Model C) Rutherford's Nuclear Model D) Bohr's Model

7. The region around the nucleus where an electron is likely to be found is called a(n):

A) Orbit B) Shell C) Orbital D) Energy level

8. What is the approximate mass of a proton?

A) 1 atomic mass unit (amu) B) 0.0005 amu C) 1836 amu D) 1.67 x 10^-19 kg

9. Which element has the atomic number 1?

A) Helium B) Hydrogen C) Lithium D) Boron

10. The periodic table is arranged in order of increasing:

A) Atomic mass B) Number of neutrons C) Atomic number D) Number of valence electrons

11. Elements in the same vertical column (group) of the periodic table have similar:

A) Atomic masses B) Number of electron shells C) Chemical properties D) Number of neutrons

12. Horizontal rows in the periodic table are called:

A) Groups B) Periods C) Series D) Blocks

13. Which group of elements are known as the alkali metals?

A) Group 1 B) Group 2 C) Group 17 D) Group 18

14. Halogens belong to which group in the periodic table?

A) Group 1 B) Group 16 C) Group 17 D) Group 18

15. Noble gases are found in which group?

A) Group 1 B) Group 15 C) Group 17 D) Group 18

16. Elements that are typically shiny, malleable, ductile, and good conductors of heat and electricity are classified as:

A) Nonmetals B) Metalloids C) Metals D) Noble gases

17. Which of the following is a nonmetal?

A) Iron B) Copper C) Sulfur D) Aluminum

18. Elements with properties intermediate between those of metals and nonmetals are called:

A) Alkali metals B) Halogens C) Metalloids D) Transition metals

19. What is the name of the element with the symbol 'K'?

A) Potassium B) Krypton C) Krypton D) Kalium

20. The atomic radius generally:

A) Increases across a period and decreases down a group B) Decreases across a period and increases down a group C) Increases across a period and increases down a group D) Decreases across a period and decreases down a group

21. Ionization energy is the energy required to:

A) Remove an electron from a neutral atom B) Add an electron to a neutral atom C) Form a chemical bond D) Increase the atomic radius

22. Electronegativity is the measure of an atom's ability to:

A) Attract electrons in a chemical bond B) Lose electrons easily C) Become a positive ion D) Conduct electricity

23. Which element has the highest electronegativity?

A) Oxygen B) Chlorine C) Fluorine D) Nitrogen

24. What is an ion?

A) An atom that has gained or lost electrons B) An atom with no neutrons C) A molecule made of two atoms D) A stable isotope

25. A positively charged ion is called a(n):

A) Anion B) Cation C) Isotope D) Molecule

26. A negatively charged ion is called a(n):

A) Anion B) Cation C) Atom D) Radical

27. The electron configuration of an element describes:

A) The number of protons in the nucleus B) The arrangement of electrons in shells and subshells C) The number of neutrons in the nucleus D) The total number of nucleons

28. The Aufbau principle states that in the ground state of an atom, electrons fill:

A) The highest energy orbitals first B) The lowest energy orbitals first C) Orbitals randomly D) Valence orbitals only

29. Hund's rule states that electrons will occupy orbitals:

A) As far apart as possible within a subshell B) Paired up in the same orbital C) In a random order D) Only in the lowest energy level

30. The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of:

A) Energy levels B) Principal quantum numbers C) Spin quantum numbers D) Four quantum numbers

31. Which element is in Period 3 and Group 16?

A) Sulfur B) Selenium C) Oxygen D) Tellurium

32. The element with electron configuration 1s²2s²2p⁶3s¹ is:

A) Magnesium B) Sodium C) Aluminum D) Silicon

33. What is the symbol for the element that is in Period 4 and Group 18?

A) Kr B) Xe C) Rn D) Ar

34. Transition metals are characterized by the filling of which orbitals?

A) s orbitals B) p orbitals C) d orbitals D) f orbitals

35. Lanthanides and Actinides are collectively known as:

A) Alkali metals B) Alkaline earth metals C) Inner transition metals D) Halogens

36. The number of valence electrons in an atom determines its:

A) Atomic mass B) Number of isotopes C) Chemical reactivity D) Number of neutrons

37. Which of the following elements has the most valence electrons?

A) Carbon (C) B) Nitrogen (N) C) Oxygen (O) D) Fluorine (F)

38. The concept of 'periodicity' in the periodic table refers to:

A) The regular variation of properties with atomic number B) The random arrangement of elements C) The constant change in atomic mass D) The stability of isotopes

39. Mendeleev's periodic table was primarily organized based on:

A) Atomic number B) Atomic mass C) Number of valence electrons D) Electronegativity

40. The modern periodic law states that the properties of elements are periodic functions of their:

A) Atomic mass B) Atomic number C) Number of neutrons D) Ionization energy

41. Which of the following is a metalloid?

A) Gold B) Silicon C) Bromine D) Argon

42. The d-block elements are also known as:

A) Main group elements B) Transition metals C) Inner transition metals D) Noble gases

43. What is the electronic configuration of Helium (He)?

A) 1s¹ B) 1s² C) 2s¹ D) 2s²

44. The element with atomic number 11 is:

A) Neon B) Sodium C) Magnesium D) Aluminum

45. Which of the following is an alkaline earth metal?

A) Lithium B) Sodium C) Potassium D) Magnesium

46. The element Krypton (Kr) is in which period?

A) Period 2 B) Period 3 C) Period 4 D) Period 5

47. What is the approximate charge of a neutron?

A) +1 B) -1 C) 0 D) +2

48. Which scientist proposed the nuclear model of the atom, where electrons orbit a dense nucleus?

A) J.J. Thomson B) Ernest Rutherford C) Niels Bohr D) James Chadwick

49. The number of protons in an atom determines its:

A) Mass number B) Atomic number C) Isotopic composition D) Ionization energy

50. What is the primary difference between isotopes of an element?

A) Number of protons B) Number of electrons C) Number of neutrons D) Charge of the nucleus

Atomic Structure and Periodic Classification - Online Test

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