Exam 1: CHEM120 / CHEM 120 (Latest
Update ) Intro to General,
Organic & Biological Chemistry with Lab |
Review Questions & Answers | Grade A |
100% Correct – Chamberlain
Question 1: What is the charge of a molecule with 18 total electrons and 16 total protons?
Answer: -2
Rationale: The charge is calculated by subtracting protons from electrons (18 electrons - 16
protons = -2). More electrons result in a negative charge.
Question 2: What is the charge of an atom with 20 protons and 18 electrons?
Answer: +2
Rationale: The charge is electrons minus protons (18 electrons - 20 protons = -2, but the atom’s
charge is +2 due to more protons).
Question 3: What is the likely outcome when chlorine (Cl) forms an ion?
Answer: Gains one electron
Rationale: Chlorine, with 7 valence electrons, gains one electron to achieve a stable octet,
forming Cl⁻.
Question 4: What defines a cation?
Answer: An ion with more protons than electrons
Rationale: A cation has a positive charge due to a net positive charge from more protons.
Question 5: What is the independent variable in an experiment?
Answer: The variable manipulated by the scientist
Rationale: The independent variable is changed to observe its effect on the dependent variable.
, Question 6: What is the purpose of a negative control in an experiment?
Answer: To ensure no response occurs
Rationale: A negative control confirms that the experiment’s conditions do not produce a false
positive result.
Question 7: What does the atomic number represent?
Answer: Number of protons in the nucleus
Rationale: The atomic number uniquely identifies an element and equals its proton count.
Question 8: What unit is used to express atomic mass?
Answer: Atomic mass units (amu)
Rationale: Atomic mass is the weighted average of an element’s isotopes, measured in amu.
Question 9: What type of bond forms between potassium and fluorine in KF?
Answer: Ionic bond
Rationale: Potassium (metal) and fluorine (non-metal) form an ionic bond via electron transfer,
creating K⁺ and F⁻.
Question 10: What is the name of the compound N₂O₅?
Answer: Dinitrogen pentoxide
Rationale: Prefixes indicate the number of atoms (di- for 2 nitrogen, penta- for 5 oxygen), with
the suffix -ide for the non-metal.
Question 11: What is the purpose of dimensional analysis in chemistry?
Answer: Convert units accurately
Rationale: Dimensional analysis uses conversion factors to ensure accurate unit conversions.
Question 12: What is the formula for density?
Answer: Density = mass/volume
Rationale: Density is calculated as mass divided by volume, typically in g/cm³ or g/mL.
Update ) Intro to General,
Organic & Biological Chemistry with Lab |
Review Questions & Answers | Grade A |
100% Correct – Chamberlain
Question 1: What is the charge of a molecule with 18 total electrons and 16 total protons?
Answer: -2
Rationale: The charge is calculated by subtracting protons from electrons (18 electrons - 16
protons = -2). More electrons result in a negative charge.
Question 2: What is the charge of an atom with 20 protons and 18 electrons?
Answer: +2
Rationale: The charge is electrons minus protons (18 electrons - 20 protons = -2, but the atom’s
charge is +2 due to more protons).
Question 3: What is the likely outcome when chlorine (Cl) forms an ion?
Answer: Gains one electron
Rationale: Chlorine, with 7 valence electrons, gains one electron to achieve a stable octet,
forming Cl⁻.
Question 4: What defines a cation?
Answer: An ion with more protons than electrons
Rationale: A cation has a positive charge due to a net positive charge from more protons.
Question 5: What is the independent variable in an experiment?
Answer: The variable manipulated by the scientist
Rationale: The independent variable is changed to observe its effect on the dependent variable.
, Question 6: What is the purpose of a negative control in an experiment?
Answer: To ensure no response occurs
Rationale: A negative control confirms that the experiment’s conditions do not produce a false
positive result.
Question 7: What does the atomic number represent?
Answer: Number of protons in the nucleus
Rationale: The atomic number uniquely identifies an element and equals its proton count.
Question 8: What unit is used to express atomic mass?
Answer: Atomic mass units (amu)
Rationale: Atomic mass is the weighted average of an element’s isotopes, measured in amu.
Question 9: What type of bond forms between potassium and fluorine in KF?
Answer: Ionic bond
Rationale: Potassium (metal) and fluorine (non-metal) form an ionic bond via electron transfer,
creating K⁺ and F⁻.
Question 10: What is the name of the compound N₂O₅?
Answer: Dinitrogen pentoxide
Rationale: Prefixes indicate the number of atoms (di- for 2 nitrogen, penta- for 5 oxygen), with
the suffix -ide for the non-metal.
Question 11: What is the purpose of dimensional analysis in chemistry?
Answer: Convert units accurately
Rationale: Dimensional analysis uses conversion factors to ensure accurate unit conversions.
Question 12: What is the formula for density?
Answer: Density = mass/volume
Rationale: Density is calculated as mass divided by volume, typically in g/cm³ or g/mL.
