OpenStax Chapter 2

What are atoms that vary in the number of neutrons found in their nuclei called?

• A. Ions
• B. Isotopes
• C. Isobars
• D. Neutral atoms

Potassium has an atomic number of 19. What is its electron configuration?

• A. Shells 1 and 2 are full, and shell 3 has 9 electrons.
• B. Shells 1, 2, and 3 are full, and shell 4 has three electrons.
• C. Shells 1, 2, and 3 are full, and shell 4 has one electron.
• D. Shells 1, 2, and 3 are full, and no other electrons are present.

Which of the following statements is false?

• A. Electrons are unequally shared in polar covalent bonds.
• A. Electrons are unequally shared in nonpolar covalent bonds.
• C. Hydrogen bonds are weak bonds based on electrostatic forces.
• D. Ionic bonds are generally stronger than covalent bonds.

If xenon has an atomic number of 54 and a mass number of 108, how many neutrons does it have?

• A. 27
• B. 54
• C. 100
• D. 108

What forms ionic bonds?

• A. atoms that share electrons equally
• B. atoms that share electrons unequally
• C. ions with similar charges
• D. ions with opposite charges

Based on the information provided, which of the following statements is false?

• A. In NH_2 the nitrogen atom acquires a partial positive charge and the hydrogen atoms acquire a partial negative charge.
• B. In H_2O, the hydrogen atoms acquire a partial negative charge, and the oxygen atom acquires a partial positive charge.
• C. In aqueous HCl, the hydrogen atom acquires a partial positive charge, and the chlorine atom acquires a partial negative charge.
• D. In LiF, the lithium atom acquires a positive charge, and the fluorine atom acquires a negative charge.

Which of the following statements is not true?

• A. Water is polar.
• B. Water can stabilize the temperature of nearby air.
• C. Water is essential for life.
• D. Water is the most abundant molecule in the Earth’s atmosphere.

Why do hydrogen and oxygen form polar covalent bonds within water molecules?

• A. Hydrogen is more electronegative than oxygen, generating a partial negative charge near the hydrogen atom.
• B. Hydrogen is more electronegative than oxygen, generating a partial positive charge near the hydrogen atom.
• C. Oxygen is more electronegative than hydrogen, generating a partial negative charge near the oxygen atoms.
• D. Oxygen is more electronegative than hydrogen, generating a partial positive charge near the oxygen atoms.

What happens to the pH of a solution when acids are added?

• A. The pH of the solution decreases.
• B. The pH of the solution increases.
• C. The pH of the solution increases and then decreases.
• D. The pH of the solution stays the same.

Which of the following statements is true?

• A. Acids and bases cannot mix together.
• B. Acids and bases can neutralize each other.
• C. Acids, not bases, can change the pH of a solution.
• D. Acids donate hydroxide ions (OH^-); bases donate hydrogen ions (H^+).