Question 1

Which of the following statements best describes the difference between a compound and a mixture?

Accepted Answer

A compound is composed of two or more elements chemically combined in fixed proportions, while a mixture is a physical combination of substances.

Question 2

Which of the following best explains why water is considered a polar molecule?

Accepted Answer

Because the oxygen atom is more electronegative than hydrogen, creating a partial negative charge on oxygen and a partial positive charge on hydrogen.

Question 3

A student dissolves 5.85 g of NaCl (molar mass = 58.5 g/mol) in enough water to make 0.500 L of solution. What is the molarity of the solution?

Accepted Answer

$$0.100\ \mathrm{M}$$

Question 4

Which of the following best describes the Law of Conservation of Mass?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 5

Which of the following electron configurations represents a noble gas?

Accepted Answer

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

Question 6

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

Accepted Answer

Because the ions are held together by strong electrostatic forces in a lattice structure.

Question 7

A balloon filled with helium gas at $$25\ ^\circ\mathrm{C}$$ and 1.00 atm has a volume of 2.00 L. If the temperature is increased to $$50\ ^\circ\mathrm{C} at $$constant pressure, what is the new volume? (Assume ideal gas behavior.)

Accepted Answer

$$2.17\ \mathrm{L}$$

Question 8

Which of the following is the correct balanced equation for the combustion of methane ($$CH_4) in $$oxygen?

Accepted Answer

$$CH_4 + 2O_2$$ \rightarrow $$CO_2 + 2H_2O$

Question 9

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 10

Which of the following best describes the difference between an exothermic and an endothermic reaction?

Accepted Answer

Exothermic reactions release heat, while endothermic reactions absorb heat.

Question 11

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

Accepted Answer

$$E = h
u$$

Question 12

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

Accepted Answer

Because the density of ice is less than that of liquid water due to hydrogen bonding.

Question 13

Which of the following is the correct expression for the ideal gas law?

Accepted Answer

$$PV = nRT$$

Question 14

Which of the following best describes the VSEPR theory?

Accepted Answer

It predicts the shapes of molecules based on the repulsion between electron pairs around a central atom.

Question 15

Which of the following is a correct statement about the quantum numbers for electrons in an atom?

Accepted Answer

The principal quantum number ($$n) $$describes the energy level of an electron.

Question 16

A sample of gas occupies 10.0 L at 2.00 atm and $$300\ \mathrm{K}. $$What volume will it occupy at 1.00 atm and $$300\ \mathrm{K}$$?

Accepted Answer

$$20.0\ \mathrm{L}$$

Question 17

Which of the following best describes the process of ionization energy?

Accepted Answer

The energy required to remove an electron from a gaseous atom.

Question 18

Which of the following is a correct statement about the relationship between wavelength ($$\lambda) $$and frequency ($$
u) of $$electromagnetic radiation?

Accepted Answer

As wavelength increases, frequency decreases.

Question 19

Which of the following best explains why sodium reacts vigorously with water?

Accepted Answer

Because sodium has a low ionization energy and readily loses its outer electron.

Question 20

Which of the following is the correct formula for calculating the percent composition by mass of an element in a compound?

Accepted Answer

$$\frac{	ext{mass of element in 1 mol of compound}}{	ext{molar mass of compound}} 	imes 100\%$$

General Chemistry I: Comprehensive Study Guide (Chapters 1–11)

Guida di studio - Domande di pratica

Study guide - Flashcard