Q: A solution has a pH of 4. What is the concentration of hydrogen ions, $$[H^+]$$, in moles per liter? Use the formula $$pH = -\log_{10}[H^+].$$

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

Question 1

Which of the following best explains why droughts are catastrophic for living organisms?

Accepted Answer

Life cannot exist without water, and droughts remove this essential resource.

Question 2

Which four elements make up about 96% of the weight of most cells?

Accepted Answer

Oxygen, Carbon, Hydrogen, Nitrogen

Question 3

A patient is diagnosed with goiter, a swelling of the thyroid gland. Which trace element deficiency is most likely responsible?

Accepted Answer

Iodine

Question 4

Which statement about isotopes is correct?

Accepted Answer

Isotopes of an element have different numbers of neutrons.

Question 5

A radioactive isotope has a half-life of 10 years. If you start with 100 grams, how much will remain after 30 years? Use the formula $$N = N_0$ 	imes (\frac{1}{2}$$)^{t/T_{1/2}$$}$$ where $$N_0 is $$the initial amount, $$t is $$time, and $$T_{1/2} is $$the half-life.

Accepted Answer

12.5 grams

Question 6

Which of the following best describes why ice floats on water?

Accepted Answer

Ice is less dense than liquid water because stable hydrogen bonds hold molecules apart.

Question 7

Which property of water is most important for the transport of water from roots to leaves in plants?

Accepted Answer

Cohesion due to hydrogen bonding

Question 8

Which of the following is an example of a compound?

Accepted Answer

Sodium chloride (NaCl)

Question 9

What type of bond is formed when two atoms share one or more pairs of electrons?

Accepted Answer

Covalent bond

Question 10

Which of the following best explains why water is a polar molecule?

Accepted Answer

Oxygen is more electronegative, so electrons spend more time near oxygen.

Question 11

A solution has a pH of 4. What is the concentration of hydrogen ions, $$[H^+]$$, in moles per liter? Use the formula $$pH = -\log_{10}[H^+].$$

Accepted Answer

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

Question 12

Which of the following statements about chemical reactions is correct?

Accepted Answer

Chemical reactions only rearrange matter.

Question 13

Which of the following best describes the role of buffers in biological systems?

Accepted Answer

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

Question 14

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

Accepted Answer

Using radioactive isotopes in PET scans to diagnose heart disorders and cancers.

Question 15

Which of the following best explains why adding fluoride to drinking water is considered beneficial?

Accepted Answer

Fluoride helps maintain healthy bones and teeth.

Question 16

Which of the following is a consequence of uncontrolled exposure to radioactive isotopes?

Accepted Answer

Damage to DNA, potentially causing cancer

Question 17

Which of the following best describes the difference between an atom and an ion?

Accepted Answer

An ion has gained or lost electrons, resulting in a net charge.

Question 18

Which of the following is a direct result of water’s high specific heat for living organisms?

Accepted Answer

Water moderates temperature changes in organisms and environments.

Question 19

Which of the following best explains why ocean acidification is a concern for marine ecosystems?

Accepted Answer

Increased CO$$_2$$ lowers ocean pH, which can harm marine life and disrupt ecological balance.

Essential Chemistry for Biology: Foundations for Life

Study Guide - Practice Questions

Study Guide - Flashcards