$$\sum (\text{isotope mass} \times \text{fractional abundance})$$

$$\text{moles} = \frac{\text{mass}}{\text{molar mass}}$$

Question 1

Which of the following statements best describes the difference between an isotope and an ion?

Accepted Answer

An isotope has a different number of neutrons, while an ion has a different number of electrons.

Question 2

Which of the following elements is most likely to form a cation?

Accepted Answer

Sodium ($$Na)$$

Question 3

A patient receives a dose of radiation measured at $$2.5$$ rem. How many mSv is this equivalent to?

Accepted Answer

$$250$$ mSv

Question 4

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

Metals have delocalized electrons that can move freely.

Question 5

Which type of radiation is most penetrating and requires the most shielding for protection?

Accepted Answer

Gamma rays

Question 6

What is the electron configuration for a neutral atom of chlorine ($$Cl$$), atomic number $$17$$?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^5$$

Question 7

Which of the following molecules exhibits hydrogen bonding?

Accepted Answer

Water ($$H_2O)$$

Question 8

A radioactive isotope decays with a half-life of $$8$$ hours. If you start with $$100 g$$, how much remains after $$24$$ hours?

Accepted Answer

$$12.5 g$$

Question 9

Which of the following best describes the VSEPR shape of methane ($$CH_4$$)?

Accepted Answer

Tetrahedral

Question 10

Which of the following is the correct formula for calculating the average atomic mass of an element?

Accepted Answer

$$\sum (	ext{isotope mass} 	imes 	ext{fractional abundance})$$

Question 11

Which of the following compounds contains a polar covalent bond?

Accepted Answer

Hydrogen chloride ($$HCl)$$

Question 12

Which of the following statements about fusion and fission is correct?

Accepted Answer

Fusion combines light nuclei into heavier nuclei, while fission splits heavy nuclei into lighter nuclei.

Question 13

Which of the following best explains why water has a higher boiling point than methane?

Accepted Answer

Water forms hydrogen bonds, which require more energy to break.

Question 14

Which of the following is the correct Lewis structure for carbon dioxide ($$CO_2$$)?

Accepted Answer

O=C=O, with each oxygen having two lone pairs

Question 15

Which of the following is the correct formula for calculating the energy absorbed by a substance when its temperature increases?

Accepted Answer

$$q = m c \Delta T$$

Question 16

Which of the following best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve transferring electrons, while covalent bonds involve sharing electrons.

Question 17

A PET scan uses which type of radioactive decay for imaging?

Accepted Answer

Positron emission

Question 18

Which of the following best explains the periodic trend in atomic radius across a period?

Accepted Answer

Atomic radius decreases due to increased nuclear charge pulling electrons closer.

Question 19

Which of the following molecules is nonpolar despite having polar bonds?

Accepted Answer

Carbon dioxide ($$CO_2)$$

Question 20

Which of the following is the correct formula for calculating the number of moles from mass and molar mass?

Accepted Answer

$$	ext{moles} = \frac{	ext{mass}}{	ext{molar mass}}$$

GOB Chemistry Study Notes: Atomic Structure, Radiation, and Chemical Bonding

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