15 free questions from the CinnaEntry HESI A2 chemistry bank (233 in the app). Tap an answer to check it. The rationale opens right away.
In a solution, the substance that is dissolved is called the:
Answer: B. Solute
The solute is dissolved into the solvent (e.g., salt is the solute in salt water).
Which is a noble gas, unreactive because its outer shell is full?
Answer: A. Helium
Noble gases (helium, neon, argon) sit in the final column with full outer shells. A full shell means no drive to react.
In the reaction 2H₂ + O₂ → 2H₂O, the substances on the LEFT are called:
Answer: A. Reactants
Reactants → products, always left to right. The arrow means 'becomes'.
In H₂O, the subscript 2 means there are two atoms of:
Answer: B. Hydrogen
The 2 applies to hydrogen, so water has two hydrogen atoms and one oxygen atom.
Which temperature scale has 0° as the freezing point of water?
Answer: A. Celsius
Celsius 0 and 100 are water's freezing and boiling points. Kelvin uses the same size degree but starts at absolute zero.
In the 'lock-and-key' model, an enzyme's shape must match its:
Answer: B. Substrate
An enzyme's active site fits a specific substrate, like a key in a lock.
The elements on the left and center of the periodic table are mostly:
Answer: B. Metals
Most elements are metals, found on the left and center of the periodic table.
To measure the mass of a small rock, the best tool is a:
Answer: A. Balance
A balance measures mass by comparison with known masses.
The atomic number of an element tells you the number of:
Answer: A. Protons
Atomic number = protons. Mass number = protons + neutrons. Change the protons and you have a different element; change the neutrons and you have an isotope.
Cooling water vapor until it becomes liquid is called:
Answer: B. Condensation
Condensation is a gas cooling into a liquid.
Mixing sand and salt, then dissolving the salt and filtering, separates them by:
Answer: B. Physical means
Filtering and dissolving are physical methods to separate a mixture.
In a chemical formula, a COEFFICIENT written in front (as in 3H₂O) indicates:
Answer: A. The number of molecules
3H₂O = three molecules, each containing 2 hydrogen and 1 oxygen — six hydrogen and three oxygen atoms in total.
When an acid and a base react together, they produce:
Answer: A. A salt and water
Acid + base → salt + water. Antacids work this way, neutralizing excess stomach acid.
Which laboratory measurement would you record in milliliters?
Answer: A. The volume of a liquid
Match quantity to unit: volume in mL or L, mass in g or kg, length in m, temperature in °C. Unit questions are free marks.
Which gas produced by burning fossil fuels contributes to air pollution?
Answer: B. Carbon dioxide
Burning fossil fuels releases carbon dioxide, a greenhouse gas and pollutant.
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