Q: A sample contains 75% $$^{35}Cl ($$atomic mass = 34.97 amu) and 25% $$^{37}Cl ($$atomic mass = 36.97 amu). What is the average atomic mass of chlorine?

$$(0.75 \times 34.97) + (0.25 \times 36.97) = 35.47$$ amu

Question 1

Rutherford’s gold foil experiment led to which major conclusion about atomic structure?

Accepted Answer

Atoms are mostly empty space with a small, dense, positively charged nucleus.

Question 2

Which of the following best explains why most alpha particles passed straight through the gold foil in Rutherford’s experiment?

Accepted Answer

Most of the atom is empty space.

Question 3

Given the isotope $$\$$displaystyle ^{132}$$_{54}\mathrm{Xe}$$, how many protons, neutrons, and electrons are present in a neutral atom?

Accepted Answer

54 protons, 78 neutrons, 54 electrons

Question 4

Which pair of atoms constitutes a pair of isotopes of the same element?

Accepted Answer

$$\$$displaystyle ^{14}$$_{6}X$$ and $$\$$displaystyle ^{12}$$_{6}X$$

Question 5

Which subatomic particle has the smallest mass?

Accepted Answer

Electron

Question 6

What is the charge and composition of an alpha particle?

Accepted Answer

2+ charge, 2 protons and 2 neutrons

Question 7

Which of the following elements is an alkaline earth metal?

Accepted Answer

Mg

Question 8

A sodium atom loses one electron to form a sodium ion. Which of the following statements is correct?

Accepted Answer

The sodium ion has 11 protons and 10 electrons.

Question 9

Which of the following compounds is a molecular compound?

Accepted Answer

N$$_2O$$

Question 10

What is the correct name for the compound FeSO$$_3$$?

Accepted Answer

iron(II) sulfite

Question 11

Which of the following ions is isoelectronic with Ne?

Accepted Answer

F$$^-$$

Question 12

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

Accepted Answer

Al$$_2O$_3$$

Question 13

Which of the following is the correct name for SO$$_2$$?

Accepted Answer

sulfur dioxide

Question 14

Which of the following acids is correctly named?

Accepted Answer

HClO$$_3 is $$chloric acid

Question 15

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 16

Which of the following ions is a cation?

Accepted Answer

Ca$$^{2+}$$

Question 17

Which of the following is the correct formula for the carbonate ion?

Accepted Answer

CO$$_3$$^{2-}$$

Question 18

A sample contains 75% $$^{35}Cl ($$atomic mass = 34.97 amu) and 25% $$^{37}Cl ($$atomic mass = 36.97 amu). What is the average atomic mass of chlorine?

Accepted Answer

$$(0.75 	imes 34.97) + (0.25 	imes 36.97) = 35.47$$ amu

Question 19

Which of the following best describes the trend in chemical properties of elements in the same group of the periodic table?

Accepted Answer

They have similar chemical properties due to similar valence electron configurations.

Question 20

Which of the following is the correct name for the compound CaCl$$_2$$?

Accepted Answer

calcium chloride

Atoms, Molecules, and Ions – General Chemistry Study Guidance

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