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Organic Chemistry and Nuclear Chemistry — High School Chemistry practice questions

23 multiple-choice questions and 14 flashcards on Organic Chemistry and Nuclear Chemistry, about 15% of the High School Chemistry bank. Every one carries a written rationale.

Written and maintained by Nick Burton · last updated 2026-08-22 · how we write and review questions

What this chapter covers

Organic Chemistry and Nuclear Chemistry is one of 12 chapters in CoStudy's High School Chemistry bank, and it holds 23 of the bank's 150 multiple-choice questions — roughly 15% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.

Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.

Free Organic Chemistry and Nuclear Chemistry practice questions

10 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.

Which is the chemical formula for water?

  1. HO
  2. HCl
  3. H₂O₂
  4. H₂O (two hydrogens, one oxygen)
  5. NaCl

Answer: D — H₂O (two hydrogens, one oxygen)

Water: H₂O. Two hydrogens bonded to one oxygen via polar covalent bonds. Bent molecular shape due to lone pairs on O. H₂O₂ is hydrogen peroxide. HCl is hydrochloric acid. NaCl is salt. Basic chemistry literacy.

What is Avogadro's number?

  1. 6.022 × 10²³ (number of particles in 1 mole)
  2. 10²³
  3. 6.022 × 10¹⁰
  4. 3.14 × 10⁸
  5. 1.6 × 10⁻¹⁹

Answer: A — 6.022 × 10²³ (number of particles in 1 mole)

Avogadro's number: 6.022 × 10²³. Number of entities (atoms, molecules, ions) per mole. Foundation of stoichiometry. Mole bridges microscopic (particles) to macroscopic (grams).

Which trend does ATOMIC RADIUS show across a period?

  1. Increases left to right
  2. No change
  3. Decreases left to right (more protons attract electrons more strongly; same energy level)
  4. Random
  5. Doubles

Answer: C — Decreases left to right (more protons attract electrons more strongly; same energy level)

Periodic trends: atomic radius DECREASES left→right (more nuclear charge, same shell pulls electrons in), INCREASES top→bottom (new electron shells added). Other trends: ionization energy INCREASES left→right, DECREASES top→bottom. Electronegativity follows similar pattern.

What are the three main subatomic particles?

  1. Protons, neutrons, electrons
  2. Protons, electrons, photons
  3. Atoms, molecules, ions
  4. Nuclei, orbitals, bonds
  5. Quarks, leptons, bosons

Answer: A — Protons, neutrons, electrons

Three main subatomic particles in atoms: protons (positive, in nucleus), neutrons (neutral, in nucleus), electrons (negative, orbiting). Atomic number = # protons. Mass number = protons + neutrons. Foundation of atomic structure.

What is a CATALYST?

  1. Consumed in reaction
  2. Heats reactions
  3. Slows reactions
  4. Changes products
  5. Substance that speeds up reaction by lowering activation energy, without being consumed

Answer: E — Substance that speeds up reaction by lowering activation energy, without being consumed

Catalyst: lowers activation energy → faster reaction. Not consumed (regenerated). Doesn't change ΔH or equilibrium position. Examples: enzymes (biological), platinum (catalytic converters), zeolites (industrial).

What is OXIDATION in a redox reaction?

  1. Gain of electrons (that's reduction)
  2. Loss of electrons (OIL: Oxidation Is Loss; oxidized species' oxidation state increases)
  3. Loss of protons
  4. Gain of protons
  5. Heat release

Answer: B — Loss of electrons (OIL: Oxidation Is Loss; oxidized species' oxidation state increases)

Redox mnemonics: OIL RIG (Oxidation Is Loss, Reduction Is Gain of electrons). LEO GER (Lose Electrons Oxidation, Gain Electrons Reduction). Oxidizing agent: gains e⁻ (gets reduced). Reducing agent: loses e⁻ (gets oxidized).

Which subatomic particle determines an atom's CHEMICAL properties?

  1. Neutrons
  2. Valence electrons (outermost shell; determine bonding and reactivity)
  3. Protons (define element identity)
  4. Nucleus
  5. Inner electrons

Answer: B — Valence electrons (outermost shell; determine bonding and reactivity)

Chemical behavior driven by valence electrons (outermost shell). Group on periodic table determined by valence count. Noble gases (full octet) inert. Halogens (7 valence) very reactive (gain 1 e). Alkali metals (1 valence) very reactive (lose 1 e).

What is the molarity of 2 moles of solute dissolved in 4 liters of solution?

  1. 0.5 M (M = mol/L = 2/4 = 0.5)
  2. 8 M
  3. 0.5
  4. 2 M
  5. 8 mol

Answer: A — 0.5 M (M = mol/L = 2/4 = 0.5)

Molarity M = moles of solute / liters of solution. 2 mol / 4 L = 0.5 M. Common solution concentration unit. Difference from molality (mol/kg solvent). HS chem solutions chapter.

Common HS Chemistry topics include:

  1. Only physics
  2. Math only
  3. Only biology
  4. Just labs
  5. Atomic structure, periodic table trends, chemical bonding, stoichiometry, gases, thermochemistry, kinetics, equilibrium, acids/bases, redox, solutions, intro to organic — aligned with NGSS HS-PS standards

Answer: E — Atomic structure, periodic table trends, chemical bonding, stoichiometry, gases, thermochemistry, kinetics, equilibrium, acids/bases, redox, solutions, intro to organic — aligned with NGSS HS-PS standards

HS Chemistry foundational: atoms → bonding → reactions → energetics → kinetics → equilibrium → acid-base → redox → solutions. NGSS HS-PS1 (Matter) and HS-PS2 (Motion) sub-strands. Prepares for AP Chemistry.

In a solution, the substance present in the greater amount is called the:

  1. Solute
  2. Concentration
  3. Solvent
  4. Volume

Answer: C — Solvent

C) Solvent: greater amount; solute: dissolved in it. A) Reverse of the definition. B) A property, not a substance. D) A physical quantity, not a component.

Organic Chemistry and Nuclear Chemistry flashcards

4 cards from the 14 in this chapter.

What are 'alkanes'?

Hydrocarbons with single bonds only. CₙH₂ₙ₊₂. Methane, ethane, propane.

What is a 'hydrocarbon'?

Compound containing only carbon and hydrogen. Like methane (CH₄).

What's an 'alpha particle'?

A helium nucleus (2 protons + 2 neutrons). Heavy, low penetration.

What is 'radioactivity'?

Spontaneous emission of particles or energy from unstable atomic nuclei.

Practise the full chapter

These are a sample. The full Organic Chemistry and Nuclear Chemistry chapter runs 37 items with per-chapter progress tracking, on the web and in the iOS app.

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