Question 1

Which of the following best describes a trace element in biological systems?

Accepted Answer

An element required in minute amounts for proper physiological functioning.

Question 2

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

Accepted Answer

Electron

Question 3

Carbon-14 is used in radiometric dating. Which statement about carbon-14 is correct?

Accepted Answer

It has 6 protons and 8 neutrons.

Question 4

Which equation correctly represents the process of photosynthesis?

Accepted Answer

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

Question 5

Which of the following best explains why ice floats on liquid water?

Accepted Answer

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

Question 6

A sodium atom (Na) has an atomic number of 11. How many valence electrons does it have?

Accepted Answer

1

Question 7

Which of the following is a correct definition of electronegativity?

Accepted Answer

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

Question 8

Which of the following is a correct structural formula for molecular oxygen (O$$_2$$)?

Accepted Answer

$$O=O$$

Question 9

Which statement best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of electron pairs between atoms.

Question 10

Which of the following molecules is both a molecule and a compound?

Accepted Answer

CO$$_2$$

Question 11

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 12

Which of the following is a correct definition of a buffer in biological systems?

Accepted Answer

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

Question 13

Which of the following is the correct charge for a sodium ion (Na) after it loses one electron?

Accepted Answer

$$+1$$

Question 14

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

Accepted Answer

Decreased availability of carbonate ions for shell formation.

Question 15

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between a hydrogen atom in one molecule and an electronegative atom in another molecule.

Question 16

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

Accepted Answer

$$	ext{Mass number} = 	ext{Number of protons} + 	ext{Number of neutrons}$$

Question 17

Which of the following statements about water is correct?

Accepted Answer

Water is a polar molecule due to unequal sharing of electrons between hydrogen and oxygen.

Question 18

Which of the following best explains why buffers are important in biological systems?

Accepted Answer

They maintain a stable pH, which is crucial for enzyme function and cellular processes.

Question 19

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

Accepted Answer

An atom or molecule with a net electric charge due to the loss or gain of electrons.

Question 20

Which of the following is a correct example of a polar covalent bond?

Accepted Answer

The bond between hydrogen and oxygen in H$$_2O.$$

Chemistry of Life: Essential Concepts for General Biology

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