Chem 121 Exam 1 Review Sheet Complete Questions Answers Graded A Plus

CHEM 121 EXAM 1 REVIEW SHEET COMPLETE QUESTIONS ANSWERS GRADED A PLUS
CHEM 121 EXAM 1 Questions and Answers Verified
Solutions Latest Update 2026/2027

Question:
Law of Conservation of Mass.

Answer:
Mass is always constant Reactant mass = Product mass They are used (upheld) in chemical
equations



Question:
Three common states of matter and their characteristics.

Answer:
- Solid (s): color Liquid (aq): melting point, solubility Gas (g):



Question:
Difference between Elements, Compounds, Homogeneous and Heterogeneous mixtures.

Answer:
- Substances: CANNOT be separated by physical process Mixture: CAN be separated by physical
process Elements: CANNOT be decomposed by chemicals Compounds: 2 or more elements
combined Homogeneous: ex: salt water Heterogeneous: physically distinct parts (ex: sand)



Question:
Difference between Physical and Chemical changes / their processes.

Answer:
Physical change: boiling, melting, change of states of matter (solid -> liquid -> gas) Chemical
change: combustion, photosynthesis, rusting

, Question:
physical vs chemical properties.

Answer:
Physical: color, melting point, solubility, boiling point Chemical: creativity in acid, ability to rust
(react with oxygen)



Question:
Precision vs Accuracy.

Answer:
Precision: closeness to "set of values obtained" (sample mean) Accuracy: closeness to true value
(population mean)



Question:
Sig Figs.

Answer:
2500 = 2 sig figs 2500.0 = 5 sig figs 0.0077 = 2 sig figs 0.03400 = 4 sig figs



Question:
Kilogram vs Gram Millogram vs Gram Nanogram vs Gram.

Answer:
1000g = 1kg 1000mg = 1g 10^-9 = 1g



Question:
3 common subatomic particles.

Answer:
1) proton 2) neutron 3) electron *only electrons can be changed