Q: Which of the following is the correct formula for calculating the atomic mass of an atom?

$$\text{Atomic mass} = \text{Number of protons} + \text{Number of neutrons} + \text{Number of electrons}$$

Question 1

Which of the following statements best explains why sodium chloride (NaCl) has properties different from those of its constituent elements, sodium and chlorine?

Accepted Answer

The formation of NaCl involves a chemical reaction that results in a compound with emergent properties distinct from its elements.

Question 2

Which of the following elements is NOT one of the four most abundant elements in living matter?

Accepted Answer

Calcium

Question 3

A patient is diagnosed with goiter due to a deficiency in which trace element?

Accepted Answer

Iodine

Question 4

Which subatomic particle determines the atomic number of an element?

Accepted Answer

Proton

Question 5

If an atom has 8 protons, 8 neutrons, and 8 electrons, what is its mass number?

Accepted Answer

$$16$$

Question 6

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 7

Radioactive isotopes are useful in biological research for all of the following EXCEPT:

Accepted Answer

Increasing the atomic mass of elements

Question 8

Which of the following best describes a covalent bond?

Accepted Answer

The sharing of a pair of valence electrons between two atoms

Question 9

What is the main difference between polar and non-polar covalent bonds?

Accepted Answer

Polar covalent bonds share electrons unequally due to differences in electronegativity, while non-polar covalent bonds share electrons equally.

Question 10

Which of the following is true about ionic bonds?

Accepted Answer

They are attractions between cations and anions after electron transfer.

Question 11

A molecule of water ($$H_2O) is $$held together by which type of bond between its atoms?

Accepted Answer

Covalent bond

Question 12

Which of the following statements about hydrogen bonds is correct?

Accepted Answer

Hydrogen bonds occur when a hydrogen atom covalently bonded to one electronegative atom is attracted to another electronegative atom.

Question 13

Which of the following best describes the role of weak chemical bonds in biological systems?

Accepted Answer

They reinforce shapes of large molecules and help molecules adhere to each other.

Question 14

What determines the chemical behavior of an atom?

Accepted Answer

The distribution of electrons in electron shells, especially the valence electrons

Question 15

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

Accepted Answer

$$	ext{Atomic mass} = 	ext{Number of protons} + 	ext{Number of neutrons} + 	ext{Number of electrons}$$

Question 16

Which of the following best explains why molecular shape is crucial in biology?

Accepted Answer

Molecular shape allows biological molecules to specifically recognize and respond to one another.

Question 17

Endorphins and morphine have similar effects in the brain because:

Accepted Answer

They bind to the same receptors due to their similar molecular shapes.

Question 18

Which of the following equations correctly represents a reversible chemical reaction?

Accepted Answer

$$3H_2 + N_2$ \rightleftharpoons 2NH_3$$

Question 19

Chemical equilibrium in a reaction is reached when:

Accepted Answer

The forward and reverse reaction rates are equal.

Question 20

Which of the following best describes a van der Waals interaction?

Accepted Answer

A weak interaction between molecules due to asymmetrical electron distribution

Chapter 2: The Chemical Context of Life – General Biology Study Notes

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