Question 1

Neon has three naturally occurring stable isotopes: $$^{20}\mathrm{Ne} (19.992 $$amu), $$^{21}\mathrm{Ne} (20.994 $$amu), and $$^{22}\mathrm{Ne} (21.991 $$amu). If the average atomic mass of Ne is 20.18 amu and the abundance of $$^{21}\mathrm{Ne} is 0.3$$%, what is the abundance of $$^{20}\mathrm{Ne}$$?

Accepted Answer

$$(90.4 \pm 0.3)\ \%$$

Question 2

Using an electric motor to raise a heavy object is an example of converting:

Accepted Answer

Electrical energy to potential energy

Question 3

What type of bond forms between selenium (Se) and oxygen?

Accepted Answer

Covalent

Question 4

If the abundance of $$^{21}\mathrm{Ne} is $$increased to 1.0% while the average atomic mass remains at 20.18 amu, what would happen to the abundance of $$^{22}\mathrm{Ne} ($$assuming only three isotopes exist)?

Accepted Answer

It would decrease

Question 5

Which of the following best describes why the bond between Se and O is covalent?

Accepted Answer

Both Se and O are nonmetals and share electrons

Question 6

A battery powers a motor that lifts a box. Which sequence of energy conversions occurs?

Accepted Answer

Chemical $$\rightarrow$$ Electrical $$\rightarrow$$ Potential

Question 7

Given the following equation for average atomic mass: $$	ext{Average mass} = \sum (	ext{isotope mass} 	imes 	ext{fractional abundance})$$, which isotope contributes most to the average atomic mass of neon?

Accepted Answer

$$^{20}\mathrm{Ne}$$

Question 8

Which of the following is a real-world example of converting electrical energy to potential energy?

Accepted Answer

Raising an elevator using an electric motor

Question 9

If a sample of neon contains 90.4% $$^{20}\mathrm{Ne}$$, 0.3% $$^{21}\mathrm{Ne}$$, and the rest is $$^{22}\mathrm{Ne}$$, what is the percent abundance of $$^{22}\mathrm{Ne}$$?

Accepted Answer

$$(9.3\%)$$

Question 10

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 11

Which of the following best explains why the average atomic mass of neon is not a whole number?

Accepted Answer

It is a weighted average of the masses of all naturally occurring isotopes

Question 12

Which of the following is NOT a plausible energy conversion in a typical household device?

Accepted Answer

Electrical energy to nuclear energy (e.g., toaster)

General Chemistry Study Guidance: Isotopes, Energy Conversion, and Chemical Bonding

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