Q: Given the following isotopic data for chlorine: $^{35}\mathrm{Cl}$ (abundance 75.8%, mass 34.969 u) and $^{37}\mathrm{Cl}$ (abundance 24.2%, mass 36.966 u), what is the average atomic mass of chlorine?

$(0.758 \times 34.969) + (0.242 \times 36.966) = 35.45\ \mathrm{u}$

Question 1

Which of the following statements correctly distinguishes between an atom and an element?

Accepted Answer

An atom is the smallest unit of an element that retains its chemical properties, while an element is a substance composed of only one type of atom.

Question 2

A neutral atom of magnesium has an atomic number of 12 and a mass number of 24. Which of the following correctly represents its full atomic symbol?

Accepted Answer

$^{24}_{12}\mathrm{Mg}$

Question 3

Which group on the periodic table is known as the noble gases, and what is a characteristic property of these elements?

Accepted Answer

Group 8A; they are chemically inert under standard conditions.

Question 4

Given the following isotopic data for chlorine: $^{35}\mathrm{Cl}$ (abundance 75.8%, mass 34.969 u) and $^{37}\mathrm{Cl}$ (abundance 24.2%, mass 36.966 u), what is the average atomic mass of chlorine?

Accepted Answer

$(0.758 	imes 34.969) + (0.242 	imes 36.966) = 35.45\ \mathrm{u}$

Question 5

Which of the following correctly describes the relationship between the wavelength ($\lambda$), frequency ($
u$), and speed of light ($c$) for electromagnetic radiation?

Accepted Answer

$c = \lambda 
u$

Question 6

Which electron transition in the hydrogen atom emits visible light according to the Bohr model?

Accepted Answer

An electron falls from $n=3$ to $n=2$

Question 7

Which of the following statements about the quantum mechanical model of the atom is correct?

Accepted Answer

Electrons occupy orbitals, which are regions of space with a high probability of finding an electron.

Question 8

How many electrons can occupy the $3p$ subshell, and how many orbitals does it contain?

Accepted Answer

6 electrons; 3 orbitals

Question 9

Which of the following is the correct condensed (noble gas core) electron configuration for calcium ($Z=20$)?

Accepted Answer

$[\mathrm{Ar}]\ 4s^2$

Question 10

Which of the following ions is most likely to be formed by a sulfur atom?

Accepted Answer

$\mathrm{S}^{2-}$

Question 11

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

Accepted Answer

Atomic size decreases due to increasing nuclear charge.

Question 12

A sample of matter is uniform throughout and can be separated into two substances by physical means. How should this sample be classified?

Accepted Answer

Homogeneous mixture

Question 13

Which of the following is a chemical change?

Accepted Answer

Iron rusting in moist air

Question 14

What is the correct formula for the ionic compound formed between aluminum and sulfate?

Accepted Answer

$\mathrm{Al}_2(\mathrm{SO}_4)_3$

Question 15

Which of the following is the correct name for $\mathrm{N}_2\mathrm{O}_5$?

Accepted Answer

Dinitrogen pentoxide

Question 16

Which of the following is the correct SI base unit for temperature?

Accepted Answer

Kelvin ($\mathrm{K}$)

Question 17

Convert $25.0\ ^\circ\mathrm{C}$ to Kelvin.

Accepted Answer

$25.0 + 273.15 = 298.15\ \mathrm{K}$

Question 18

A student measures the mass of a metal cylinder as $13.42\ \mathrm{g}$ and its volume as $2.7\ \mathrm{cm}^3$. What is the density of the metal, reported with the correct number of significant figures?

Accepted Answer

$4.97\ \mathrm{g/cm}^3$

Question 19

Which of the following numbers has the greatest number of significant figures?

Accepted Answer

$0.004560$

Question 20

A hospital solution contains $0.90\ \mathrm{g}$ of sodium chloride per $100.0\ \mathrm{mL}$ of solution. What is the concentration in $\mathrm{mg/mL}$?

Accepted Answer

$9.0\ \mathrm{mg/mL}$

Chem 101 Exam 1 Study Guide: Chapters 1–4

Study Guide - Practice Questions

Study Guide - Flashcards