Q: A sample contains $$3.0\ \mathrm{mol} of $$sodium atoms. How many atoms are present in the sample? (Avogadro's number $$= 6.022 \times 10$$^{23}$$\ \mathrm{atoms/mol})$$

$$1.81 \times 10$$^{24}$$ atoms

Question 1

Which of the following best describes a scientific law?

Accepted Answer

A statement that summarizes a pattern found in nature, often expressed mathematically, such as $$F = ma.$$

Question 2

Which of the following is a physical change?

Accepted Answer

Melting of ice into water.

Question 3

A student measures the mass of a sample as $$12.5\ \mathrm{g}$$ and its volume as $$5.0\ \mathrm{cm}^3. $$What is the density of the sample?

Accepted Answer

$$2.5\ \mathrm{g/cm}^3$$

Question 4

Which of the following statements about Dalton's Atomic Theory is correct?

Accepted Answer

Atoms of the same element are identical in mass and properties.

Question 5

Which scientist is credited with discovering the electron?

Accepted Answer

J.J. Thomson

Question 6

Which of the following is the correct SI prefix and symbol for $$10^{-6}$$?

Accepted Answer

micro ($$\mu)$$

Question 7

A sample contains $$3.0\ \mathrm{mol} of $$sodium atoms. How many atoms are present in the sample? (Avogadro's number $$= 6.022 	imes 10$$^{23}$$\ \mathrm{atoms/mol})$$

Accepted Answer

$$1.81 	imes 10$$^{24}$$ atoms

Question 8

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 9

Which of the following elements is classified as a metalloid?

Accepted Answer

Silicon (Si)

Question 10

Which of the following is the correct electron configuration for a neutral atom of carbon ($$Z=6$$)?

Accepted Answer

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

Question 11

Which of the following best explains why Mendeleev's periodic table was significant?

Accepted Answer

He arranged elements by increasing atomic mass and predicted the properties of undiscovered elements.

Question 12

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 13

Which of the following is a correct conversion between units?

Accepted Answer

$$1\ \mathrm{cm}^3 = 1\ \mathrm{mL}$$

Question 14

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 15

Which of the following best describes a cation?

Accepted Answer

An ion with a positive charge formed by losing one or more electrons.

Question 16

A sample of gold has a mass of $$19.3\ \mathrm{g}$$ and a volume of $$1.00\ \mathrm{cm}^3. $$What is the density of gold?

Accepted Answer

$$19.3\ \mathrm{g/cm}^3$$

Question 17

Which of the following is a chemical property?

Accepted Answer

Ability of iron to rust when exposed to oxygen.

Question 18

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

Accepted Answer

A compound has a fixed composition and chemical bonds between elements, while a mixture does not.

Question 19

Which of the following is the correct order of increasing atomic radius for the elements Na, Mg, and Al?

Accepted Answer

Al \u003c Mg \u003c Na

Question 20

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have a full valence shell of electrons.

Introduction to Chemistry: Key Concepts and Study Guide

Study Guide - Practice Questions

Study Guide - Flashcards