Question 1

Which of the following best describes a trace element?

Accepted Answer

An element required by an organism in minute quantities for proper biological function.

Question 2

Given the atomic symbol $$^{14}C$$, how many neutrons does this isotope of carbon contain?

Accepted Answer

8

Question 3

Which of the following statements correctly explains why ice floats on water?

Accepted Answer

Hydrogen bonds in ice create a lattice that spaces water molecules farther apart, making ice less dense than liquid water.

Question 4

Which of the following molecules is most likely to form hydrogen bonds with water?

Accepted Answer

Ammonia ($$NH_3)$$

Question 5

A solution has a pH of 4. How many times more acidic is it than a solution with a pH of 7?

Accepted Answer

$$1000$$ times

Question 6

Which of the following best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve the transfer of electrons from one atom to another, while covalent bonds involve the sharing of electrons between atoms.

Question 7

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

Accepted Answer

12

Question 8

Which of the following best explains how a buffer works in a biological system?

Accepted Answer

A buffer maintains a constant pH by neutralizing added acids or bases.

Question 9

Which of the following compounds is most likely to dissolve in water?

Accepted Answer

Sodium chloride ($$NaCl)$$

Question 10

What is the maximum number of electrons that can occupy the second electron shell of an atom?

Accepted Answer

8

Question 11

Which of the following best describes the role of valence electrons in chemical bonding?

Accepted Answer

Valence electrons determine the number of covalent bonds an atom can form.

Question 12

A neutral atom of sodium ($$Na) $$has 11 protons and 11 electrons. If it loses one electron, what is its resulting charge?

Accepted Answer

$$+1$$

Question 13

Which of the following is a property of water that results from hydrogen bonding?

Accepted Answer

High surface tension

Question 14

Which of the following best describes a chemical reaction?

Accepted Answer

A process in which atoms are rearranged to form new substances.

Question 15

Which of the following statements about acids and bases is correct?

Accepted Answer

Acids increase the concentration of $$H^+$$ ions in solution.

Question 16

If you add a strong acid to a neutral solution, what will happen to the pH?

Accepted Answer

The pH will decrease.

Question 17

Which of the following best explains why water is an effective solvent for ionic compounds?

Accepted Answer

Water molecules surround and separate ions due to their polarity.

Question 18

Which of the following is true about radioactive isotopes?

Accepted Answer

They emit radiation as they decay to a more stable form.

Question 19

Which of the following best describes surface tension in water?

Accepted Answer

It is caused by the attraction between water molecules at the surface due to hydrogen bonding.

Question 20

Which of the following is the correct formula for calculating the number of neutrons in an atom?

Accepted Answer

$$	ext{Number of neutrons} = 	ext{Mass number} - 	ext{Atomic number}$$

Essential Chemistry for Biology: Study Guide and Key Concepts

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