Question 1

Which of the following statements best explains why atoms form chemical bonds?

Accepted Answer

Atoms form bonds to achieve a full outer electron shell, increasing stability.

Question 2

Which element is most electronegative among the following, and what effect does this have on covalent bonds?

Accepted Answer

Oxygen; it attracts shared electrons more strongly, creating polar covalent bonds.

Question 3

A radioactive isotope of carbon, $$^{14}C$$, is used in dating fossils. What makes $$^{14}C$$ radioactive compared to $$^{12}C$$?

Accepted Answer

$$^{14}C$$ has an unstable nucleus due to extra neutrons.

Question 4

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the attraction between oppositely charged ions.

Question 5

If a sodium atom ($$Na) $$loses one electron, what is its resulting charge and what is it called?

Accepted Answer

It becomes positively charged and is called a cation.

Question 6

Which of the following molecules is most likely to form hydrogen bonds with water?

Accepted Answer

Ammonia ($$NH_3)$$

Question 7

What is the mass number of an atom with 6 protons and 8 neutrons?

Accepted Answer

$$14$$

Question 8

Which of the following best describes a polar covalent bond?

Accepted Answer

Electrons are shared unequally, resulting in partial charges on atoms.

Question 9

A molecule of water ($$H_2O) $$has a bent shape. Why is the shape of a molecule important in biology?

Accepted Answer

Shape affects how molecules interact with biological receptors and enzymes.

Question 10

Which of the following is NOT a use of radioactive isotopes in biology?

Accepted Answer

Increasing the atomic number of elements.

Question 11

Which of the following elements is NOT one of the four most abundant elements in living organisms?

Accepted Answer

Phosphorus

Question 12

What is the atomic number of an atom, and how is it determined?

Accepted Answer

The number of protons in the atom.

Question 13

Which type of chemical bond is responsible for the attraction between water molecules?

Accepted Answer

Hydrogen bond

Question 14

A magnesium ion ($$Mg^{2+}) is $$formed when magnesium:

Accepted Answer

Loses two electrons.

Question 15

Which of the following best describes van der Waals interactions?

Accepted Answer

Weak attractions between molecules due to temporary charge differences.

Question 16

If an atom has 11 protons, 12 neutrons, and 10 electrons, what is its net charge?

Accepted Answer

$$+1$$

Question 17

Which of the following is true about isotopes of an element?

Accepted Answer

They have the same number of protons but different numbers of neutrons.

Question 18

Which of the following best explains why noble gases like helium are chemically inert?

Accepted Answer

They have full outer electron shells, making them stable.

Question 19

A chlorine atom ($$Cl) $$gains one electron to become $$Cl^-. $$What type of ion is this?

Accepted Answer

Anion

Question 20

Which of the following best describes the role of chemical bonds in biological molecules?

Accepted Answer

They hold atoms together, forming molecules essential for cell structure and function.

The Chemical Context of Life: Foundations for General Biology

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