unit 4 chemistry test

What are the correct coefficients for balancing the equation:
___ Al + ___ O₂ → ___ Al₂O₃ ?
A) 2, 3, 1
B) 4, 3, 2
C) 2, 1, 1
D) 3, 2, 1

B) 4, 3, 2

In a balanced chemical equation, the coefficients represent:
A) The number of grams of each substance
B) The relative numbers of atoms in a molecule
C) The relative numbers of moles of each substance
D) The relative densities of each substance

C) The relative numbers of moles of each substance

Which of the following equations is balanced correctly?
A) H₂ + Cl₂ → HCl
B) 2H₂ + O₂ → 2H₂O
C) Na + Cl₂ → 2NaCl
D) 2Mg + O₂ → MgO

B) 2H₂ + O₂ → 2H₂O

When balancing equations, polyatomic ions should:
A) Always be broken into individual atoms
B) Be ignored
C) Be kept together if they appear unchanged on both sides
D) Be multiplied by atomic masses

C) Be kept together if they appear unchanged on both sides

Which type of reaction is represented by:
2H₂O₂ → 2H₂O + O₂ ?
A) Synthesis
B) Decomposition
C) Single Replacement
D) Combustion

B) Decomposition

What type of reaction is represented by:
2Na + Cl₂ → 2NaCl ?
A) Double replacement
B) Combustion
C) Synthesis
D) Decomposition

C) Synthesis

Which of the following reactions is a single replacement reaction?
A) Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag
B) CaCO₃ → CaO + CO₂
C) H₂ + Cl₂ → 2HCl
D) AgNO₃ + NaCl → AgCl + NaNO₃

A) Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag

What are the products of the combustion of propane (C₃H₈) in oxygen?
A) CO₂ and H₂O
B) CO and H₂
C) CH₄ and CO₂
D) H₂ and C

A) CO₂ and H₂O

According to the activity series, which of the following reactions will occur?
A) Zn + CuSO₄ → ZnSO₄ + Cu
B) Cu + ZnSO₄ → CuSO₄ + Zn
C) Ag + HCl → AgCl + H₂
D) Au + H₂O → Au₂O₃ + H₂

A) Zn + CuSO₄ → ZnSO₄ + Cu

Which of the following represents a double replacement reaction?
A) 2KClO₃ → 2KCl + 3O₂
B) 2NaOH + CuSO₄ → Na₂SO₄ + Cu(OH)₂
C) CH₄ + 2O₂ → CO₂ + 2H₂O
D) 2H₂ + O₂ → 2H₂O

B) 2NaOH + CuSO₄ → Na₂SO₄ + Cu(OH)₂

The molar mass of calcium nitrate, Ca(NO₃)₂, is approximately:
A) 102 g/mol
B) 118 g/mol
C) 164 g/mol
D) 236 g/mol

C) 164 g/mol

How many moles of oxygen are required to completely react with 4.0 mol of hydrogen to form water?
2H₂ + O₂ → 2H₂O

A) 1.0 mol
B) 2.0 mol
C) 4.0 mol
D) 8.0 mol

B) 2.0 mol

How many molecules are in 2.00 moles of CO₂?
A) 1.20 × 10²³
B) 3.01 × 10²³
C) 6.02 × 10²³
D) 1.20 × 10²⁴

D) 1.20 × 10²⁴

What mass of H₂O is produced when 4.00 g of hydrogen reacts completely with excess oxygen?
2H₂ + O₂ → 2H₂O
A) 18.0 g
B) 36.0 g
C) 72.0 g
D) 4.00 g

B) 36.0 g

In the reaction N₂ + 3H₂ → 2NH₃, how many moles of NH₃ are produced from 1.5 mol of H₂?
A) 0.5 mol
B) 1.0 mol
C) 1.5 mol
D) 3.0 mol

B) 1.0 mol

In the reaction 2H₂ + O₂ → 2H₂O, if 3.0 mol H₂ and 2.0 mol O₂ are mixed, which is the limiting reactant?
A) H₂
B) O₂
C) H₂O
D) Neither, both are in excess

A) H₂

The limiting reactant is the reactant that:
A) Is present in the smallest mass
B) Has the smallest molar mass
C) Is used up first
D) Is left over after the reaction

C) Is used up first

If 4.0 g of hydrogen reacts with 32.0 g of oxygen, what mass of water forms?
2H₂ + O₂ → 2H₂O
A) 18.0 g
B) 36.0 g
C) 36.0 g
D) 36.0 g

B) 36.0 g

The molarity of a solution is defined as:
A) Moles of solute per gram of solvent
B) Moles of solute per kilogram of solvent
C) Moles of solute per liter of solution
D) Grams of solute per liter of solvent

C) Moles of solute per liter of solution

What is the molarity of a solution containing 0.5 mol NaCl in 2.0 L of solution?
A) 0.25 M
B) 0.50 M
C) 1.0 M
D) 2.0 M

A) 0.25 M

The molality of a solution is defined as:
A) Moles of solute per liter of solution
B) Moles of solute per kilogram of solvent
C) Grams of solute per liter of solvent
D) Moles of solute per mole of solvent

B) Moles of solute per kilogram of solvent

Which of the following statements is true about molarity and molality?
A) Molarity changes with temperature; molality does not
B) Molality changes with temperature; molarity does not
C) Both change with temperature
D) Neither changes with temperature

A) Molarity changes with temperature; molality does not

Which compound is insoluble in water?
A) NaNO₃
B) K₂SO₄
C) AgCl
D) NH₄Cl

C) AgCl

Which of the following compounds would form a precipitate when solutions are mixed?
A) NaOH + HCl
B) Na₂CO₃ + CaCl₂
C) KNO₃ + NaCl
D) HNO₃ + NH₄Cl

B) Na₂CO₃ + CaCl₂

Which of the following is a strong electrolyte?
A) Glucose (C₆H₁₂O₆)
B) H₂O
C) NaCl
D) NH₃

C) NaCl

When acids react with bases, the products are:
A) A salt and hydrogen gas
B) A salt and water
C) A gas and a solid
D) A new acid and new base

B) A salt and water

Which of the following is soluble in water?
A) PbSO₄
B) BaSO₄
C) Na₂CO₃
D) AgBr

C) Na₂CO₃

Which solution has the lowest freezing point?
A) 1.0 M NaCl
B) 1.0 M glucose
C) 0.5 M CaCl₂
D) 0.5 M urea

A) 1.0 M NaCl

Colligative properties depend on:
A) The type of solute
B) The color of the solution
C) The number of solute particles
D) The mass of solvent only

C) The number of solute particles

A 1.0 m solution of NaCl will have approximately:
A) The same boiling point as pure water
B) A lower boiling point than pure water
C) A higher boiling point than pure water
D) The same freezing point as pure water

C) A higher boiling point than pure water