1.10 MC Answers and Review

⛔STOP ! ⛔ Before you look at the answers, make sure you gave this practice quiz a try so you can assess your understanding of the concepts covered in Unit 1. Click here for the practice questions: AP Chemistry Unit 1 Multiple Choice Questions.

Facts about the test: The AP Chemistry exam has 60 multiple choice questions and you will be given 1 hour 30 minutes to complete the section. That means it should take you around 15 minutes to complete 10 questions.

(B) Nitrogen-15

(C) Phosphorus-30

(D) Zinc-65

Answer: All of these isotopes are written with their mass number. The mass number is the number of protons plus neutrons. Manganese has 25 protons; therefore, 55-25 = 30 neutrons.

📄 Study AP Chemistry Unit 1.2 - Mass Spectroscopy of Elements

(A) 496 kJ/mol and 110 pm

(B) 496 kJ/mol and 180 pm

(D) 789 kJ/mol and 180 pm

Answer: When comparing elements in the same row, one must look at the number of protons the element has. Since silicon has more protons in its nucleus, it is better at attracting its electrons than aluminum is. This makes the first ionization energy greater and the radius smaller.

📄 Study AP Chemistry Unit 1.6 - Photoelectron Spectroscopy & Graph Interpretation

(B) 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^4

(C) 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^6

(D) 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^8

Answer: When electrons are removed from atoms, they are removed from the valence shell, which for iron is the fourth energy level. The valence electrons are the electrons in the highest energy level. Therefore, the electron configuration of Fe^2+ is 1s^2 2s^2 2p^6 3s^2 3p^6 3d^6.

📄 Study AP Chemistry Unit 1.5 - Atomic Structure and Electron Configurations

(B) K Cl

(C) Na Cl

(D) Rb Cl

Answer: The percent composition of chlorine in LiCl is greatest, therefore, in samples of the same mass, the mass of chlorine will be greatest in the sample with the greatest mass percent.

📄 Study AP Chemistry Unit 1.1 - Moles and Molar Mass

(B) Mg, because it has a full sub-shell of electrons.

(C) Na, because it has a greater electronegativity

(D) Na, because of its greater mass.

Answer: When comparing two elements in the same period, one must consider the nuclear charge. The nuclear charge refers to the number of protons, of which magnesium contains more. with more protons, Mg has a greater force of attraction on its electrons.

📄 Study AP Chemistry Unit 1.6 - Photoelectron Spectroscopy & Graph Interpretation

(A) Carbon has a greater electronegativity than silicon.

(B) Carbon has a smaller atomic radius.

(D) Silicon's valence electrons occupy a larger energy level.

Answer: When comparing electrons in the same sub-level, one must compare the number of protons in the nucleus. More protons increases the nuclear charge and increases the attraction of a respective sub-level.

📄 Study AP Chemistry Unit 1.6 - Photoelectron Spectroscopy & Graph Interpretation

(B) Be, because it has four valence electrons.

(C) O, because it has two valence electrons.

(D) O, because it has six valence electrons.

Answer: The number of valence electrons is indicated by the large increase in the ionization energy. The jump occurs between the second ionization and the third, indicating that there are two valence electrons.

📄 Study AP Chemistry Unit 1.8 - Valence Electrons and Ionic Compounds

(A) C_2 H

(B) C H

(D) C H_4

Answer: Carbon and hydrogen are in a 1mol:2mol ratio respectively.

📄 Study AP Chemistry Unit 1.1 - Moles and Molar Mass

(A) 8 g of oxygen gas (O_2)

(C) 22 g of carbon dioxide (CO_2)

(D) 110 g of lead (Pb)

Answer: Since the molar mass of Carbon is ~12 g/mol, this is the only sample that contains roughly 1 mol of particles. All the other values contain less than one mole.

📄 Study AP Chemistry Unit 1.1 - Moles and Molar Mass

(B) C_4 H_8 O

(C) C_4 H_16 O_2

(D) C_24 H_8 O_16

Answer: Carbon, hydrogen, and oxygen are in a 2mol C : 8mol H : 1mol O ratio

📄 Study AP Chemistry Unit 1.1 - Moles and Molar Mass

(A) Atomic Radius

(B) Electronegativity

(C) Electron Affinity

Answer: Ionization energy is defined as the amount of energy required to remove an electron from an atom.

📄 Study AP Chemistry Unit 1.6 - Photoelectron Spectroscopy & Graph Interpretation

(A) Chlorine

(C) Neon

(D) Nitrogen

Answer: Fluorine has 9 electrons that are defined by the electron configuration in the image.

📄 Study AP Chemistry Unit 1.5 - Atomic Structure and Electron Configurations

(A) C H_2 and C_2 H_4

(C) Oxygen-19 and Fluorine-19

(D) Water (H_2 O) and hydrogen peroxide (H_2 O_2)

Answer: Isotopes are defined as elements of the same element with different numbers of neutrons.

📄 Study AP Chemistry Unit 1.2 - Mass Spectroscopy of Elements

(A) Beryllium

(B) Carbon

(D) Sodium

Answer: Magnesium has the electron configuration of 1s^2 2s^2 2p^6 3s^2. This is represented by the photo electron spectrum.

📄 Study AP Chemistry Unit 1.5 - Atomic Structure and Electron Configurations

(A) 1.20 x 10^23 atoms of carbon

(C) 6.02 x 10^23 atoms of carbon

(D) 6.02 x 10^24 atoms of carbon

📄 Study AP Chemistry Unit 1.6 - Photoelectron Spectroscopy & Graph Interpretation