Q: A sample of carbon contains 98.892% $$^{12}C ($$mass = 12.00000 amu) and 1.108% $$^{13}C ($$mass = 13.00335 amu). What is the average atomic mass of carbon?

$$(0.98892 \times 12.00000) + (0.01108 \times 13.00335) = 12.011$$ amu

Question 1

Which of the following statements is NOT a postulate of Dalton's Atomic Theory?

Accepted Answer

Atoms can be subdivided into protons, neutrons, and electrons.

Question 2

Which experiment led to the discovery that atoms have a small, dense, positively charged nucleus?

Accepted Answer

Rutherford's gold foil experiment

Question 3

A neutral atom of sodium has an atomic number of 11 and a mass number of 23. How many neutrons does it contain?

Accepted Answer

$$23 - 11 = 12$$ neutrons

Question 4

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 5

Which of the following elements is a diatomic molecule in its natural state?

Accepted Answer

Oxygen ($$O_2)$$

Question 6

A sample of carbon contains 98.892% $$^{12}C ($$mass = 12.00000 amu) and 1.108% $$^{13}C ($$mass = 13.00335 amu). What is the average atomic mass of carbon?

Accepted Answer

$$(0.98892 	imes 12.00000) + (0.01108 	imes 13.00335) = 12.011$$ amu

Question 7

Which of the following best explains why ionic compounds, such as sodium chloride, have high melting points?

Accepted Answer

They are held together by strong electrostatic forces between oppositely charged ions.

Question 8

Which of the following ions is isoelectronic with neon ($$Ne$$)?

Accepted Answer

$$Na^+$$

Question 9

What is the correct formula for a compound formed between aluminum and oxygen?

Accepted Answer

$$Al_2O_3$$

Question 10

Which of the following is the correct name for $$N_2O_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 11

Which of the following statements about metals and nonmetals is correct?

Accepted Answer

Metals are ductile and have a shiny luster.

Question 12

A certain element forms a $$2+$$ ion and is located in Group 2A of the periodic table. Which element is it most likely to be?

Accepted Answer

Magnesium ($$Mg)$$

Question 13

Which of the following is the correct name for $$CuSO_4$$ \cdot 5H_2O$$?

Accepted Answer

Copper(II) sulfate pentahydrate

Question 14

Which of the following best describes the difference between a molecular formula and an empirical formula?

Accepted Answer

A molecular formula shows the actual number of atoms of each element in a molecule, while an empirical formula shows the simplest whole-number ratio of atoms.

Question 15

Which of the following is the correct name for $$FeCl_3$$?

Accepted Answer

Iron(III) chloride

Question 16

Which of the following best explains why the periodic table is arranged by atomic number rather than atomic mass?

Accepted Answer

Atomic number corresponds to the number of protons, which defines the element.

Question 17

Which of the following is the correct formula for the compound formed between calcium and chlorine?

Accepted Answer

$$CaCl_2$$

Question 18

Which of the following is the correct name for $$SO_3$$?

Accepted Answer

Sulfur trioxide

Question 19

Which of the following best describes a cation?

Accepted Answer

An atom or molecule that has lost electrons and has a positive charge.

Question 20

Which of the following is the correct name for $$H_2SO_4$$?

Accepted Answer

Sulfuric acid

Atoms, Molecules, and Ions: Foundations of Matter

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