Q: A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$the solution?

$$[H^+] = 1 \times 10$$^{-4}$$ M

Question 1

Which of the following best explains why iodine is added to table salt in many countries?

Accepted Answer

To prevent thyroid gland problems by ensuring sufficient hormone production

Question 2

A patient is given a radioactive isotope for medical imaging. Which property of radioactive isotopes makes them useful for this purpose?

Accepted Answer

They emit detectable radiation as they decay, allowing tracking in the body

Question 3

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

Accepted Answer

An element contains only one type of atom, while a compound contains two or more elements chemically combined

Question 4

Which of the following statements about protons, neutrons, and electrons is correct?

Accepted Answer

Protons and neutrons have nearly the same mass, while electrons are much lighter

Question 5

A certain atom has an atomic number of 8 and a mass number of 18. How many neutrons does it have?

Accepted Answer

$$18 - 8 = 10$$ neutrons

Question 6

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between a hydrogen atom covalently bonded to one electronegative atom and another electronegative atom

Question 7

Which of the following is a real-world consequence of ocean acidification?

Accepted Answer

Decreased ability of marine organisms to form calcium carbonate shells

Question 8

Which property of water allows insects to walk on its surface?

Accepted Answer

Surface tension due to hydrogen bonding

Question 9

Why does ice float on liquid water?

Accepted Answer

Hydrogen bonds in ice create a lattice that is less dense than liquid water

Question 10

A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$the solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$ M

Question 11

Which of the following best explains how buffers help maintain pH in biological systems?

Accepted Answer

Buffers donate or accept hydrogen ions to minimize changes in pH

Question 12

Which of the following is an example of a chemical reaction?

Accepted Answer

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

Question 13

Which of the following best describes the difference between heat and temperature?

Accepted Answer

Heat is the total amount of energy due to molecular motion, while temperature measures the intensity of that motion

Question 14

Why is water considered a universal solvent in biological systems?

Accepted Answer

Its polar molecules can surround and dissolve many ionic and polar compounds

Question 15

A scientist is searching for signs of life on Mars. According to current scientific understanding, why is the search for water so important in this context?

Accepted Answer

All known life depends on water's unique properties for chemical reactions and stability

Question 16

Which of the following best describes the role of iron as a trace element in the human body?

Accepted Answer

Iron is a component of hemoglobin, essential for oxygen transport in blood

Question 17

Which of the following statements about covalent bonds is correct?

Accepted Answer

Covalent bonds involve the sharing of electron pairs between atoms

Question 18

A solution is made by dissolving 10 g of NaCl in 100 mL of water. In this solution, which term best describes NaCl?

Accepted Answer

Solute

Question 19

Which of the following best explains why sweating cools the human body?

Accepted Answer

Sweat absorbs heat as it evaporates, due to water's high heat of vaporization

Question 20

Which of the following best describes the effect of adding a base to a solution?

Accepted Answer

It decreases the hydrogen ion concentration $$[H^+]$$

The Chemical Basis of Life: Study Notes for General Biology

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