Question 1

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

Accepted Answer

An element is a pure substance consisting of only one type of atom, while a compound consists of two or more elements chemically combined in fixed ratios.

Question 2

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

Accepted Answer

Carbon, hydrogen, oxygen, and nitrogen

Question 3

A trace element is best defined as:

Accepted Answer

An element required by an organism in minute quantities for proper physiological functioning

Question 4

Which subatomic particle is directly involved in chemical reactions between atoms, and what is its charge?

Accepted Answer

Electron; negative charge

Question 5

If an atom has an atomic number of 8 and a mass number of 16, how many neutrons does it have?

Accepted Answer

$$16 - 8 = 8$$ neutrons

Question 6

Which of the following best explains why water is an excellent solvent?

Accepted Answer

Water molecules are polar, allowing them to surround and separate ions and polar molecules.

Question 7

What type of bond is found in molecular oxygen ($$O_2$$)?

Accepted Answer

Nonpolar covalent bond

Question 8

Which statement about valence electrons is correct?

Accepted Answer

Valence electrons determine the chemical behavior of an atom.

Question 9

What is the main cause of a goiter in humans?

Accepted Answer

Deficiency of the trace element iodine

Question 10

Which of the following best describes a hydrogen bond?

Accepted Answer

A bond formed by the attraction between a hydrogen atom with a partial positive charge and an electronegative atom with a partial negative charge

Question 11

Which property of water allows a water spider to walk on its surface?

Accepted Answer

Surface tension due to hydrogen bonding

Question 12

What happens to the concentration of sugar in coffee if more sugar is added?

Accepted Answer

The concentration of sugar increases

Question 13

Which of the following is true about acids and bases?

Accepted Answer

An acid is a molecule that adds $$H^+$$ ions to a solution.

Question 14

How many times more acidic is a solution with a pH of 3 compared to a solution with a pH of 5?

Accepted Answer

$$100$$ times

Question 15

What is the role of buffers in biological systems?

Accepted Answer

Buffers minimize changes in pH by accepting or donating $$H^+$$ ions.

Question 16

Which of the following best describes electronegativity?

Accepted Answer

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

Question 17

Which of the following molecules is a compound but not a molecule?

Accepted Answer

None; all compounds are molecules

Question 18

What is the chemical equation for cellular respiration?

Accepted Answer

$$C_6H_{12}O_6$ + 6O_2 ightarrow 6H_2O + 6CO_2 + 	ext{energy (ATP)}$$

Question 19

Which statement best explains why ice floats on water?

Accepted Answer

Ice is less dense than liquid water because hydrogen bonds hold water molecules further apart in the solid state.

Question 20

Which two ions are formed when water dissociates?

Accepted Answer

Hydronium ion ($$H_3O^+) $$and hydroxide ion ($$OH^-)$$

General Biology Study Guide: Chemistry of Life, Water, and pH

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