Question 1

Which of the following statements best explains why sodium chloride (NaCl) has properties different from those of its constituent elements?

Accepted Answer

Compounds have emergent properties that differ from the properties of the individual elements that compose them.

Question 2

Which element makes up the largest percentage of body mass in humans?

Accepted Answer

Oxygen

Question 3

An atom of carbon-14 ($$^{14}C) $$has how many protons, neutrons, and electrons?

Accepted Answer

6 protons, 8 neutrons, 6 electrons

Question 4

Which of the following best describes a trace element?

Accepted Answer

An element required by an organism in minute quantities

Question 5

Which of the following is true about isotopes?

Accepted Answer

Isotopes of an element have different numbers of neutrons but the same number of protons.

Question 6

Which equation correctly represents the balanced chemical reaction for the formation of water from hydrogen and oxygen?

Accepted Answer

$$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 7

Which type of chemical bond involves the sharing of a pair of valence electrons between two atoms?

Accepted Answer

Covalent bond

Question 8

What is the main reason that atoms with incomplete valence shells are chemically reactive?

Accepted Answer

They seek to complete their valence shell by gaining, losing, or sharing electrons.

Question 9

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond in which electrons are shared unequally between atoms of different electronegativity.

Question 10

Which of the following statements about chemical reactions is correct?

Accepted Answer

Chemical reactions must be balanced so that all atoms in the reactants are accounted for in the products.

Question 11

Which of the following is a real-world application of radioactive isotopes?

Accepted Answer

They are used as tracers to track atoms through metabolism.

Question 12

If an atom has an atomic number of 11 and a mass number of 23, how many neutrons does it have?

Accepted Answer

$$23 - 11 = 12$$ neutrons

Question 13

Which of the following best explains why molecular shape is important in biology?

Accepted Answer

Molecular shape affects the function of molecules in a cell, such as binding to receptors.

Question 14

Which of the following interactions is the weakest type of chemical bond but can collectively have significant effects?

Accepted Answer

Van der Waals interactions

Question 15

Which statement about valence electrons is correct?

Accepted Answer

The number of valence electrons determines the chemical behavior of an atom.

Question 16

Which of the following is an example of a nonpolar covalent bond?

Accepted Answer

The bond between two hydrogen atoms in $$H_2$$

Question 17

Which of the following best describes the difference between an element and a compound?

Accepted Answer

A compound consists of two or more elements in a fixed ratio, while an element cannot be broken down by chemical reactions.

Question 18

Which of the following is true about chemical equilibrium?

Accepted Answer

At equilibrium, the forward and reverse reactions occur at the same rate.

Question 19

Which of the following best describes the role of orbitals in chemical bonding?

Accepted Answer

Orbitals are three-dimensional spaces where electrons are likely to be found, and their overlap allows for covalent bonding.

Chapter 2: The Chemical Context of Life – Study Notes

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