Atomic Theory and Chemistry Multiple-Choice Quiz PDF

Atomic Theory and Chemistry Multiple-Choice Quiz Section 1: Historical Theories and Discoveries 1. Who first theorized that matter is made up of tiny, indivisible particles called atoms? A) John Dalton B) J.J. Thomson C) Democritus (Answer: C) D) Ernest Rutherford 2. Which...

Atomic Theory and Chemistry Multiple-Choice Quiz Section 1: Historical Theories and Discoveries 1. Who first theorized that matter is made up of tiny, indivisible particles called atoms? A) John Dalton B) J.J. Thomson C) Democritus (Answer: C) D) Ernest Rutherford 2. Which scientist is credited with developing the first comprehensive atomic theory? A) Democritus B) John Dalton (Answer: B) C) J.J. Thomson D) Eugene Goldstein 3. Who discovered the electron? A) John Dalton B) J.J. Thomson (Answer: B) C) Ernest Rutherford D) Niels Bohr 4. Eugene Goldstein is known for discovering which subatomic particle? A) Electron B) Proton (Answer: B) C) Neutron D) Positron 5. Who discovered the neutron? A) J.J. Thomson B) James Chadwick (Answer: B) C) John Dalton D) Niels Bohr 6. What experiment led Ernest Rutherford to conclude that atoms have a small, dense nucleus? A) The Cathode Ray Tube Experiment B) The Gold Foil Experiment (Answer: B)  C) The Oil Drop Experiment D) The Plum Pudding Experiment 7. Which scientist proposed the "Plum Pudding" model of the atom? A) John Dalton B) J.J. Thomson (Answer: B) C) Ernest Rutherford D) Niels Bohr Section 2: Dalton’s Atomic Theory 8. Which of the following is NOT a part of Dalton’s atomic theory? A) All matter is composed of atoms. B) Atoms cannot be divided into smaller parts. C) All atoms of an element are identical in mass and properties. D) Atoms can change into other elements during chemical reactions. (Answer: D) 9. According to Dalton’s theory, how do atoms of different elements differ from each other? A) They have different numbers of electrons. B) They have different masses and properties. (Answer: B) C) They have different numbers of protons. D) They have different shapes. 10. Dalton’s atomic theory states that compounds are formed when atoms of different elements combine in simple whole-number ratios. Which of the following compounds follows this principle? A) Water (H₂O) B) Carbon Dioxide (CO₂) C) Ammonia (NH₃) D) All of the above (Answer: D) Section 3: Subatomic Particles and Their Discoveries 11. How did J.J. Thomson determine that the particles he discovered were negatively charged? A) By observing their deflection in a magnetic field. (Answer: A)  B) By measuring their mass-to-charge ratio. C) By using the Gold Foil Experiment. D) By detecting their interactions with protons. 12. What is the charge of a neutron? A) Positive B) Negative C) Neutral (Answer: C) D) It varies 13. Which subatomic particle has a positive charge? A) Electron B) Proton (Answer: B) C) Neutron D) All of the above 14. What is the mass number of an atom? A) The number of protons. B) The number of neutrons. C) The sum of protons and neutrons. (Answer: C) D) The number of electrons. Section 4: Atomic Structure and Properties 15. What does the atomic number of an element represent? A) The total number of neutrons in an atom. B) The total number of protons in an atom. (Answer: B) C) The sum of protons and neutrons. D) The charge of the atom. 16. What is the atomic mass of an element? A) The number of protons in the nucleus. B) The number of neutrons in the nucleus. C) The sum of protons and neutrons in the nucleus. D) The weighted average mass of all naturally occurring isotopes. (Answer: D) 17. What are isotopes?  A) Atoms with the same number of protons but different numbers of neutrons. (Answer: A) B) Atoms with different numbers of protons but the same number of neutrons. C) Atoms that have the same atomic mass. D) Atoms that have the same atomic number and mass number. 18. What does the mass number represent? A) The number of protons. B) The number of electrons. C) The sum of protons and neutrons. (Answer: C) D) The charge of the nucleus. Section 5: Ions and Their Properties 19. What is an ion? A) An atom that has gained or lost protons. B) An atom that has gained or lost neutrons. C) An atom that has gained or lost electrons. (Answer: C) D) An atom with no charge. 20. What is a cation? A) A positively charged ion. (Answer: A) B) A negatively charged ion. C) An atom with no charge. D) An atom that gained electrons. 21. What is an anion? A) A positively charged ion. B) A negatively charged ion. (Answer: B) C) An atom with no charge. D) An atom that lost electrons. 22. Which type of ion is formed when an atom loses electrons? A) Cation (Answer: A) B) Anion C) Neutron D) Proton 23. Which type of ion is formed when an atom gains electrons?  A) Cation B) Anion (Answer: B) C) Neutron D) Proton 24. Which group of elements tends to gain electrons? A) Metals B) Nonmetals (Answer: B) C) Noble gases D) Metalloids 25. Which group of elements tends to lose electrons? A) Nonmetals B) Noble gases C) Metals (Answer: C) D) Metalloids 26. What are protons and neutrons collectively called? A) Isotopes B) Ions C) Nucleons (Answer: C) D) Subatomic particles Section 6: Quantitative Problems 27. If in a sample of 50 atoms, 15 are isotope A, 30 are isotope B, and 5 are isotope C, which isotope is the most abundant? A) Isotope A B) Isotope B (Answer: B) C) Isotope C D) All isotopes are equally abundant. 28. In a sample of 40 atoms, 10 are isotope X, 20 are isotope Y, and 10 are isotope Z. What is the percent abundance of isotope Y? A) 25% B) 50% (Answer: B) C) 75% D) 100% 29. If isotope 1 has a mass of 3.50 g, isotope 2 has a mass of 1.50 g, and isotope 3 has a mass of 5.00 g, and the average atomic mass of the element is 4.90 g, which isotope is the most abundant? A) Isotope 1 (Answer: A) B) Isotope 2 C) Isotope 3 D) All isotopes are equally abundant. 30. Calculate the average atomic mass of an element with two isotopes: Isotope A: Mass = 10 amu, Abundance = 20% Isotope B: Mass = 12 amu, Abundance = 80% A) 10.0 amu B) 11.2 amu C) 11.6 amu (Answer: C) D) 12.0 amu 31. An element has two isotopes: Isotope X: Mass = 6 amu, Abundance = 25% Isotope Y: Mass = 8 amu, Abundance = 75% Question: What is the average atomic mass of the element? A) 6.5 amu B) 7.0 amu C) 7.5 amu **(Answer: C Example: Let's calculate the atomic mass of chlorine. Chlorine has two isotopes: Cl-35 (mass = 34.969 amu, percent abundance = 75.8%) Cl-37 (mass = 36.966 amu, percent abundance = 24.2%) Step 1: Convert percent abundance into a fraction: Cl-35: 75.8% = 0.758 Cl-37: 24.2% = 0.242 Step 2: Use the formula to calculate the atomic mass: Average Atomic Mass=(34.969×0.758)+(36.966×0.242)\text{Average Atomic Mass} = (34.969 \times 0.758) + (36.966 \times 0.242)Average Atomic Mass=(34.969×0.758)+(36.966×0.242) =26.497+8.950= 26.497 + 8.950=26.497+8.950 =35.447 amu= 35.447 \text{ amu}=35.447 amu So, the average atomic mass of chlorine is approximately 35.45 amu. MA’CARO RESTAURANT