Question 1

Which of the following best describes an element?

Accepted Answer

A pure substance that cannot be broken down into other substances by chemical means

Question 2

Which four elements make up approximately 96% of living matter?

Accepted Answer

Carbon, Hydrogen, Oxygen, Nitrogen

Question 3

What is the atomic number of carbon, and what does it represent?

Accepted Answer

6; the number of protons in the nucleus

Question 4

Which of the following is a trace element essential for human health?

Accepted Answer

Iron

Question 5

Given the following chemical equation for photosynthesis, which molecule is the product?

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2$$

Accepted Answer

$$C_6H_{12}O_6$

Question 6

Which statement correctly describes a covalent bond?

Accepted Answer

It is formed by the sharing of electrons between atoms

Question 7

What is the difference between a polar covalent bond and a non-polar covalent bond?

Accepted Answer

Polar covalent bonds have unequal sharing of electrons, while non-polar covalent bonds have equal sharing

Question 8

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 9

A sodium atom (Na) has 11 protons. How many electrons does a neutral sodium atom have?

Accepted Answer

11

Question 10

Which subatomic particle is directly involved in chemical reactions between atoms?

Accepted Answer

Electron

Question 11

What is the structural formula for molecular oxygen ($$O_2$$)?

Accepted Answer

$$O=O$$

Question 12

Which of the following best describes electronegativity?

Accepted Answer

The ability of an atom to attract electrons in a chemical bond

Question 13

Which of the following is a correct equation for the dissociation of carbonic acid in seawater, contributing to ocean acidification?

$$H_2CO_3 \rightarrow $$HCO_3$$^- + H^+$$

Accepted Answer

$$H_2CO_3 \rightarrow $$HCO_3$$^- + H^+$$

Question 14

Why does ice float on liquid water?

Accepted Answer

Ice is less dense than liquid water because hydrogen bonds hold water molecules further apart in ice

Question 15

Which of the following best describes a buffer in biological systems?

Accepted Answer

A substance that maintains a stable pH by accepting or donating $$H^+$$ ions

Question 16

Which of the following is an example of a molecule but NOT a compound?

Accepted Answer

Oxygen ($$O_2)$$

Question 17

Which of the following statements about hydrogen bonds is correct?

Accepted Answer

Hydrogen bonds occur between molecules, not within them

Question 18

Which of the following is a correct definition of an ion?

Accepted Answer

An atom or molecule with a net electrical charge due to loss or gain of electrons

Question 19

Which of the following best explains why ocean acidification is harmful to marine organisms such as corals?

Accepted Answer

It lowers the pH, reducing the availability of carbonate ions needed for calcium carbonate formation

Question 20

Which of the following best describes an aqueous solution?

Accepted Answer

A solution in which water is the solvent

Chemistry of Life: Foundations for General Biology

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