Question 1

Which statement best describes the particulate nature of matter as discussed in General Chemistry?

Accepted Answer

Matter is made up of discrete particles such as atoms, ions, and molecules.

Question 2

Which of the following is a homogeneous mixture?

Accepted Answer

Salt dissolved in water.

Question 3

Which representation of water ($\mathrm{H_2O}$) shows its molecular structure?

Accepted Answer

A diagram showing two hydrogen atoms bonded to one oxygen atom.

Question 4

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 5

A chemist wants to determine the number of atoms in a 10.0 g sample of carbon ($\mathrm{C}$). Which calculation should they perform?

Accepted Answer

Convert grams to moles using $\mathrm{moles = \frac{mass}{molar\ mass}}$, then multiply by Avogadro's number.

Question 6

Which of the following is NOT a correct way to classify matter?

Accepted Answer

By its color: red, blue, or green.

Question 7

Which equation correctly relates the number of moles ($n$), mass ($m$), and molar mass ($M$) of a substance?

Accepted Answer

$n = \frac{m}{M}$

Question 8

A sample contains $3.00 	imes 10^{24}$ atoms of magnesium ($\mathrm{Mg}$). How many moles of magnesium are present? ($N_A = 6.022 	imes 10^{23}\ \mathrm{mol}^{-1}$)

Accepted Answer

$4.98\ \mathrm{mol}$

Question 9

Which of the following statements about ions is correct?

Accepted Answer

An ion is an atom or molecule with a net electrical charge due to the loss or gain of electrons.

Question 10

Which of the following best explains why scientific models of atoms are revised over time?

Accepted Answer

Because new experimental evidence leads to improved understanding.

Question 11

Which of the following is a correct symbolic representation for sodium ion?

Accepted Answer

$\mathrm{Na^+}$

Question 12

A neutral atom of chlorine ($\mathrm{Cl}$) has 17 protons, 18 neutrons, and 17 electrons. What is the mass number of this atom?

Accepted Answer

$35$

Question 13

Which of the following is true about the relationship between atoms and molecules?

Accepted Answer

Atoms combine to form molecules through chemical bonds.

Question 14

Which of the following is a correct statement about the difference between a compound and a mixture?

Accepted Answer

A compound is made of two or more elements chemically bonded, while a mixture is made of substances physically combined.

Question 15

Which of the following best describes the macroscopic view of matter?

Accepted Answer

Measuring the boiling point of water in a laboratory.

Question 16

Which of the following is the correct definition of atomic number?

Accepted Answer

The number of protons in the nucleus of an atom.

Question 17

A sample of copper ($\mathrm{Cu}$) contains $2.00\ \mathrm{mol}$ of atoms. How many atoms are present?

Accepted Answer

$1.20 	imes 10^{24}$ atoms

Question 18

Which of the following is a correct statement about chemical bonds?

Accepted Answer

Chemical bonds involve the sharing or transfer of electrons between atoms.

Question 19

Which of the following is the correct formula to calculate the number of atoms in a given mass of an element?

Accepted Answer

$	ext{Number of atoms} = \frac{	ext{mass}}{	ext{molar mass}} 	imes N_A$

Question 20

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture in which the individual components are not evenly distributed.

Atoms: Structure, Representation, and Quantitative Relationships

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