Grade 10 · Chemistry
Biology, chemistry, and physics questions from US classrooms. Written in American English for students, parents, and teachers in the United States.
Open a card to see the answer. These are original practice items for US elementary students — not a state test copy.
Answer: +1
Electrons are −1; neutrons are 0.
Answer: number of protons, different neutrons
Carbon-12 and carbon-14 are isotopes.
Answer: similar chemical properties
Noble gases are Group 18.
Answer: row
Period 2 has Li through Ne.
Answer: has gained or lost electrons
Na⁺ lost one electron.
Answer: shares electrons
H₂O has covalent bonds.
Answer: a metal and a nonmetal
NaCl is ionic.
Answer: in the outermost shell and drive bonding
The group number often hints at valence count for main groups.
Answer: 6.022 × 10²³ particles (Avogadro’s number)
A mole is a counting unit.
Answer: 18 g/mol
2(1) + 16 = 18.
Answer: 44 g/mol
12 + 32 = 44.
Answer: mass (g) / molar mass (g/mol)
n = m/M.
Answer: 2 mol
36/18 = 2.
Answer: 22.4 L
This is a common US chemistry search.
Answer: 58.5 g/mol
23 + 35.5 ≈ 58.5.
Answer: mole ratios of reactants and products
2H₂ + O₂ → 2H₂O means 2 mol H₂ per 1 mol O₂.
Pick the next article in this topic — that is how a magazine issue is meant to be used.
