Question 1

Which of the following best describes a chemical change?

Accepted Answer

Iron rusting when exposed to air

Question 2

A sample of seawater is analyzed in a laboratory. Which classification best describes seawater?

Accepted Answer

Homogeneous mixture

Question 3

Which of the following is a physical property?

Accepted Answer

Density

Question 4

A student measures the mass of a coin as 2.34 g, 2.35 g, and 2.33 g in three trials. The actual mass is 2.50 g. Which statement best describes the measurements?

Accepted Answer

Low accuracy, high precision

Question 5

Convert 25.0 °C to Kelvin using the equation $$ K = ^\circ C + 273.15 .$$

Accepted Answer

$$ 298.15\ K $$

Question 6

How many significant figures are in the measurement 0.004560?

Accepted Answer

4

Question 7

A student needs to convert 5.00 inches to centimeters. Given $$ 1\ 	ext{inch} = 2.54\ 	ext{cm} $$, what is the correct answer with the proper number of significant figures?

Accepted Answer

$$ 12.7\ 	ext{cm} $$

Question 8

Which scientist is credited with discovering the electron using the cathode ray tube experiment?

Accepted Answer

Thomson

Question 9

An atom of $$ ^{35}_{17}Cl $$ has how many protons, neutrons, and electrons?

Accepted Answer

17 protons, 18 neutrons, 17 electrons

Question 10

Which of the following best describes the trend in atomic size across a period from left to right in the periodic table?

Accepted Answer

Atomic size decreases

Question 11

Which of the following elements is a metalloid?

Accepted Answer

Silicon (Si)

Question 12

What is the electron configuration for a neutral atom of magnesium ($$ Z = 12 $$)?

Accepted Answer

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

Question 13

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

Accepted Answer

$$ F^- $$

Question 14

A naturally occurring element has two isotopes: $$ ^{10}B  (19.9$$%, mass = 10.013 amu) and $$ ^{11}B  (80.1$$%, mass = 11.009 amu). What is the average atomic mass of boron? (Round to 3 decimal places)

Accepted Answer

$$ 10.812\ 	ext{amu} $$

Question 15

Which of the following statements about the octet rule is correct?

Accepted Answer

Atoms tend to gain, lose, or share electrons to achieve 8 electrons in their outermost shell

Question 16

Which of the following best describes the trend in ionization energy as you move down a group in the periodic table?

Accepted Answer

Ionization energy decreases

Question 17

A neutral atom of sulfur ($$ S ) $$forms an anion. What is the charge of the most common ion formed, and how many electrons does it have?

Accepted Answer

$$ 2- $$ charge, 18 electrons

Question 18

Which of the following is a chemical property of hydrogen gas?

Accepted Answer

It reacts explosively with oxygen

Question 19

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture with visibly different parts or phases

Question 20

A patient receives 250 mL of a saline solution. If $$ 1\ 	ext{L} = 1000\ 	ext{mL} $$, how many liters did the patient receive?

Accepted Answer

$$ 0.25\ 	ext{L} $$

CHE 121 General Chemistry Study Guide – Step-by-Step Guidance

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