Chemistry Sample Exams

How many electrons does it take to completely fill the 2p subshell?

6 electrons are needed to completely fill the 2p subshell.

Which of the following elements is a noble gas?

Helium (He) is a noble gas.

Which substance exhibits the smallest temperature change when 1.0 g is exposed to 1.0 J of heat energy?

Water (4.18 J/g∙ °C) exhibits the smallest temperature change.

Which of the following pairs of numbers have the larger number written first?

I and III have the larger number written first.

How many unpaired electrons does a carbon atom have in the ground state electron configuration?

A carbon atom has 2 unpaired electrons.

Which of the options below has the same number of neutrons as 80Br?

81Kr has the same number of neutrons as 80Br.

Which of the following statements concerning the characteristics of matter is FALSE?

The chemical composition of metallic iron changes during rusting is FALSE.

Which of the following diagrams represent(s) a pure substance?

Diagram I only represents a pure substance.

The first electron of oxygen (O) resides in what type of orbital?

The first electron of oxygen resides in an s orbital.

What neutral element does the electron configuration 1s22s22p63s1 describe?

The electron configuration describes sodium (Na).

Which of the following electron configurations cannot exist for atoms in their ground state?

[Ne]2s22p3 cannot exist in the ground state.

What is the boiling point of the substance depicted by the cooling curve?

The boiling point cannot be determined without the identity of the substance.

What is the number of valence electrons for an element with the electron configuration 1s22s22p63s23p64s23d104p3?

The element has 5 valence electrons.

What is the percent abundance of the isotope with mass of 36.97 amu if the other isotope has an abundance of 75.76%?

The percent abundance of the isotope with mass of 36.97 amu is 24.24%.

What is the mass of copper found in a 2.00 g sample of bronze with 52.0% copper?

The mass of copper is 1.04 g.

Which of the following statements regarding mixtures is FALSE?

Gasoline is an example of a heterogeneous mixture is FALSE.

What is the final temperature of a 20.0 g piece of metallic iron exposed to 681 J of heat energy?

The final temperature is 100.3 °C.

For the equation 2k/3 = k - 3/3, what is the value of k?

The value of k is 9.

Which of the following is equivalent to 275 °C?

275 °C is equivalent to 527 °F.

Which one of the following is the correct electron configuration for a ground-state nitrogen atom?

The correct electron configuration for nitrogen is 1s22s22p3.

Which number below is listed correctly in scientific notation?

0.000710 is correctly listed as 7.1 x 10^-4.

What is the mass of water if 155 kJ of heat is added to vaporize it at 100 °C?

The mass of the water sample is 68.6 g.

What is the total amount of nutritional Calories obtained by a tablespoon of clover honey containing 17 g of carbohydrate?

The total amount of nutritional Calories is 68 Cal.

What is the temperature at 40 minutes on the graph?

The temperature at 40 minutes is 44 °C.

What is a strong electrolyte?

A strong electrolyte is a substance that completely dissociates into ions when dissolved in water, allowing it to conduct electricity effectively.

How does temperature affect gas pressure?

According to Gay-Lussac's law, if the volume and amount of gas are constant, increasing the temperature of a gas will increase its pressure.

What is the ideal gas law?

The ideal gas law is a relation between pressure (P), volume (V), temperature (T), and the number of moles (n) of a gas, expressed as PV = nRT, where R is the ideal gas constant.

What is STP in chemistry?

STP stands for Standard Temperature and Pressure, defined as 0 degrees Celsius (273.15 K) and 1 atmosphere (atm) pressure.

What is the Kinetic Molecular Theory?

The Kinetic Molecular Theory explains the behavior of gases, stating that gas particles are in constant motion, collide elastically, and occupy a volume much larger than their size.

What is a limiting reactant?

A limiting reactant is the substance that is completely consumed in a chemical reaction, limiting the amount of product formed.

How do you calculate dilution?

Dilution can be calculated using the formula C1V1 = C2V2, where C1 and V1 are the concentration and volume of the stock solution, and C2 and V2 are the concentration and volume of the diluted solution.

What is percent by mass?

Percent by mass is a way of expressing the concentration of a solution, calculated as (mass of solute / mass of solution) x 100%.

What is solubility?

Solubility is the maximum amount of solute that can dissolve in a given amount of solvent at a specific temperature and pressure.

What is a saturated solution?

A saturated solution is a solution that contains the maximum amount of solute that can dissolve at a given temperature and pressure.

What is an unsaturated solution?

An unsaturated solution is a solution that contains less solute than the maximum amount that can dissolve at a given temperature and pressure.

What is the pressure of a gas?

The pressure of a gas is the force exerted by the gas particles colliding with the walls of its container, typically measured in atmospheres (atm) or mmHg.

What is the relationship between moles and volume at STP?

At STP, one mole of an ideal gas occupies 22.4 liters of volume.

What is the formula for calculating pressure using the ideal gas law?

The formula for calculating pressure using the ideal gas law is P = nRT/V, where P is pressure, n is the number of moles, R is the ideal gas constant, and V is volume.

What is the significance of the periodic table in chemistry?

The periodic table organizes all known elements based on their atomic number, electron configuration, and recurring chemical properties, serving as a fundamental tool in chemistry.

What is the role of temperature in gas behavior?

Temperature affects the kinetic energy of gas particles; as temperature increases, the kinetic energy and pressure of the gas also increase, assuming volume is constant.

What is the relationship between solubility and temperature?

For many solids, solubility increases with temperature, while for gases, solubility typically decreases as temperature increases.

What is the formula for calculating the number of moles?

The number of moles can be calculated using the formula n = mass (g) / molar mass (g/mol).

What is the pressure of gas A?

0.500 atm

What is the pressure of gas B?

0.263 atm

What is the pressure of gas C?

0.567 atm

What is the pressure of gas D?

0.389 atm

What is the pressure of gas E?

1.34 atm

If the pressure of a constant amount of gas at constant temperature is increased by threefold, what happens to its volume?

The volume is one-third of the original volume.

How many liters of O2 (g) are needed to react completely with 56.0 L of CH4 (g) at STP?

28.0 L

What mass of NH3 is needed to completely react with 0.450 moles of O2 (g)?

7.66 g NH3

What is the heat of the reaction for 2 H2O2(l) → 2 H2O(l) + O2(g)?

The reaction is exothermic and heat is released by this reaction.

What is the total pressure of a gas mixture containing O2 and Ne with partial pressures of 766 torr and 0.88 atm?

1.89 atm

What is the suitable procedure for preparing 500. mL of a 0.120 M aqueous CaCl2 solution?

In a flask, dissolve 6.66 g of CaCl2, in sufficient water to make a 500. mL solution.

What is the volume (mL) of a 12.0 M HCl solution that contains 3.60 moles of HCl?

300 mL

How many grams of solid Fe(OH)2 are formed when 175 mL of 2.27 M aqueous LiOH reacts with excess aqueous FeCl2?

51.0 g

What is the equilibrium expression for the reaction 2H2S (g) ⇌ 2H2 (g) + S2 (g)?

Kc = [H2]^2 [S2] / [H2S]^2

What is the best estimate of the time that equilibrium is established based on the concentration plot?

2 hrs

What is the mass of water produced when 8.23 g of C4H10 reacts with 35.7 g O2?

132 g

Which aqueous solution would have the highest osmotic pressure?

1 M CaCl2

Which pair of compounds will form a solution?

Benzene (C6H6) and hexane (C6H14)

What is the volume of a container filled with 0.644 g of O2 gas at 5.00 °C under 1.112 atm pressure?

Volume calculation required using ideal gas law.

What is the charge on Sn in the ionic compound SnO?

The charge on Sn in SnO is +2.

What is the strongest type of intermolecular forces present between molecules of liquid NF3?

The strongest type of intermolecular forces in NF3 is dipole-dipole attractions.

Which of the following covalent bonds are considered non-polar?

The non-polar covalent bonds are O-O and F-F (II and IV).

How many moles of NH3 are needed to completely react with 0.600 moles of O2?

1.20 mol NH3 are needed to completely react with 0.600 moles of O2.

Which molecule is predicted to have the highest boiling point?

CH3OH is predicted to have the highest boiling point.

How many molecules of CO2 are in 0.0180 moles of CO2?

There are 2.80 × 10^23 molecules of CO2 in 0.0180 moles.

What is the formula of an ionic compound formed from calcium and hydroxide ions?

The formula is Ca(OH)2.

How many total bonding electrons are in the correct Lewis structure of N2H2?

There are 8 total bonding electrons in the Lewis structure of N2H2.

Which of the following have a predicted bond angle of 109°?

The tetrahedral molecular geometry has a predicted bond angle of 109°.

Why do metals become cations?

Metals have lower ionization energies, making it more likely to lose electrons.

What is the name of PCl5?

The name is phosphorus pentachloride.

Which of the following molecules does not have a triple bond present in the correct Lewis structure?

CS2 does not have a triple bond present in its Lewis structure.

How many picometers (pm) are there in 2.56 mm?

There are 2.56 × 10^10 pm in 2.56 mm.

How many total electrons does N3- have?

N3- has a total of 10 electrons.

Which of the following calculation setups would convert centimeters to feet?

The correct setup is cm x 1 inch x 12 ft / 2.54 cm.

What is the name of Cu(NO2)2?

The name is copper(II) nitrate.

What are the coefficients for the reactants and products that are needed to balance the reaction of C3H8 and O2?

The coefficients are 1, 5, 3, 4.

Which of the following numbers has 4 significant figures?

The numbers 2710 and 8034 have 4 significant figures.

How many oxygen (O) atoms are present in 0.0765 moles of C14H14O3?

There are 1.38 × 10^23 oxygen atoms in 0.0765 moles of C14H14O3.

What does Ni (s) do in the reaction Ni (s) → Ni2+ (aq) + 2e-?

Ni (s) is oxidized.

How many chlorine (Cl) atoms are in a 15 gram sample of CaCl2?

There are 2.4 × 10^24 Cl atoms in a 15 gram sample of CaCl2.

What value should be reported for the length of the pencil?

The properly reported length is 15.9 cm.

What type of classification best characterizes the reaction 2HBr (g) → H2 (g) + Br2 (g)?

The reaction is a decomposition reaction.

What is the correct number of significant figures for the calculation (12.315 + 6.085)?

The correct number of significant figures is 0.085.

What is the mass, in grams, of 0.150 moles of I2?

The mass of 0.150 moles of I2 is 38.1 g.

How many liters are in 0.030 m3?

There are 30.0 L in 0.030 m3.

What is the equilibrium concentration of SO3 for the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g) with Kc = 429?

The equilibrium concentration of SO3 is 3.62 × 10-1 M.

What is the [H3O+] of a solution with a pH of 5.00 at 25 °C?

The [H3O+] is 1.0 × 10-5 M.

Which pair represents an acid followed by its conjugate base?

H2SO4 / SO42-.

What does Kc = 1.33 indicate about the equilibrium of A(g) ⇌ B(g) at 273 K?

It indicates that the concentrations of A and B are at a specific ratio at equilibrium.

Which equilibrium constant represents a reaction that favors the reactants to the greatest extent?

Kc = 1.0 × 10-18.

What scenario favors the forward reaction for 2H2S(g) ⇌ 2H2(g) + S2(g) with ΔH = +130 kJ?

Heating the reaction mixture favors the forward reaction.

What is the concentration of OH- if [H3O+] is 1.5 × 10-5 M at 25 °C?

The concentration of OH- is 4.0 × 10-13 M.

What is the acid dissociation expression for hydrofluoric acid (HF) reacting with water?

HF + H2O ⇌ H3O+ + F-.