Question 1

Which of the following statements best describes a scientific theory as discussed in Chapter 1?

Accepted Answer

A scientific theory is a well-substantiated explanation of some aspect of the natural world that can incorporate laws, hypotheses, and facts.

Question 2

A student measures the mass of a sample three times and records the values: 2.51 g, 2.50 g, and 2.52 g. The true mass is 2.80 g. Which statement best describes the accuracy and precision of these measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 3

Which of the following is a chemical property?

Accepted Answer

Flammability of gasoline

Question 4

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{CH}_2\mathrm{O}$$

Question 5

Which of the following best describes the difference between a homogeneous and a heterogeneous mixture?

Accepted Answer

A homogeneous mixture has a uniform composition throughout, while a heterogeneous mixture does not.

Question 6

A sample of nitrogen gas occupies 2.50 L at 1.00 atm and 300 K. What will be its volume at 2.00 atm and 300 K, assuming ideal gas behavior?

Accepted Answer

$$1.25\ \mathrm{L}$$

Question 7

Which of the following statements about atomic structure is correct according to modern quantum theory?

Accepted Answer

Electrons are found in specific energy levels, but their exact position cannot be known simultaneously with their momentum.

Question 8

Which of the following elements has the highest first ionization energy?

Accepted Answer

Neon ($$\mathrm{Ne})$$

Question 9

Which of the following molecules is nonpolar, despite having polar bonds?

Accepted Answer

$$\mathrm{CO}_2$$

Question 10

A reaction has $$\Delta H = -125\ \mathrm{kJ}$$ and $$\Delta S = +50\ \mathrm{J/K}. At $$what temperature (in K) does the reaction become nonspontaneous?

Accepted Answer

$$2500\ \mathrm{K}$$

Question 11

Which of the following best explains why ice floats on water?

Accepted Answer

Ice is less dense than liquid water because its molecules form an open hexagonal structure due to hydrogen bonding.

Question 12

Which of the following is the correct electron configuration for a ground-state sulfur atom ($$Z=16$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^4$$

Question 13

Which of the following best describes the shape of a molecule with four bonding pairs and no lone pairs on the central atom?

Accepted Answer

Tetrahedral

Question 14

Which of the following is a correct statement about the periodic table?

Accepted Answer

Elements in the same group have the same number of valence electrons.

Question 15

A 0.500 mol sample of $$\mathrm{NaCl} is $$dissolved in enough water to make 1.00 L of solution. What is the molarity of the solution?

Accepted Answer

$$0.500\ \mathrm{M}$$

Question 16

Which of the following best describes the process of oxidation in a redox reaction?

Accepted Answer

Loss of electrons by a substance

Question 17

Which of the following is the correct balanced equation for the combustion of propane ($$\mathrm{C}_3\mathrm{H}_8$$)?

Accepted Answer

$$\mathrm{C}_3\mathrm{H}_8 + 5\ \mathrm{O}_2 \rightarrow 3\ \mathrm{CO}_2 + 4\ \mathrm{H}_2\mathrm{O}$$

Question 18

Which of the following best explains why ionic compounds tend to have high melting points?

Accepted Answer

They are composed of ions held together by strong electrostatic forces.

Question 19

Which of the following is the correct formula for calculating the energy of a photon?

Accepted Answer

$$E = h 
u$$

Question 20

A sample of gas is collected over water at $$25^\circ \mathrm{C}$$ and a total pressure of $$755\ \mathrm{mmHg}. $$The vapor pressure of water at this temperature is $$24\ \mathrm{mmHg}. $$What is the partial pressure of the dry gas?

Accepted Answer

$$731\ \mathrm{mmHg}$$

Chem 140: Final Exam Prep – Comprehensive Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard