Q: Which equation correctly represents the calculation of the mass number of an atom?

$\text{Mass Number} = \text{Number of Protons} + \text{Number of Neutrons}$

Question 1

Which four elements make up approximately 96% of the human body's weight and are the main ingredients of sugars, fats, proteins, and nucleic acids?

Accepted Answer

Carbon, Hydrogen, Oxygen, Nitrogen

Question 2

A patient presents with an enlarged thyroid gland (goiter). Which trace element deficiency is most likely responsible, and what is the physiological reason?

Accepted Answer

Iodine; it is required for thyroid hormone production

Question 3

Which statement best explains why sodium chloride (NaCl) is edible, even though its constituent elements are a reactive metal and a poisonous gas?

Accepted Answer

Compounds have entirely different properties than their constituent elements

Question 4

What is the main difference between isotopes of the same element?

Accepted Answer

They have different numbers of neutrons

Question 5

Which type of chemical bond is formed when one atom donates an electron to another atom, resulting in the formation of ions?

Accepted Answer

Ionic bond

Question 6

Given the electron configuration, which element is most likely to form four covalent bonds?

Accepted Answer

Carbon

Question 7

Why does ice float on water, even though solids are usually denser than liquids?

Accepted Answer

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

Question 8

Which equation correctly represents the calculation of the mass number of an atom?

Accepted Answer

$	ext{Mass Number} = 	ext{Number of Protons} + 	ext{Number of Neutrons}$

Question 9

A solution has a pH of 5. Which of the following statements is true?

Accepted Answer

The solution is acidic

Question 10

Which property of water allows it to dissolve ionic compounds such as NaCl?

Accepted Answer

Water is a polar molecule

Question 11

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak non-covalent bond between a hydrogen atom with a partial positive charge and an electronegative atom with a partial negative charge

Question 12

If a molecule has atoms with very different electronegativities, what type of covalent bond will likely form?

Accepted Answer

Polar covalent bond

Question 13

Which of the following is a trace element required for oxygen transport in blood?

Accepted Answer

Iron

Question 14

What happens to the temperature of water when hydrogen bonds are broken?

Accepted Answer

Temperature increases as molecules move faster

Question 15

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

Accepted Answer

Evaporation removes the hottest molecules, lowering the temperature of the remaining liquid

Question 16

Which of the following is true about the electron shells of atoms?

Accepted Answer

Atoms are most stable when their outer shell contains 8 electrons

Question 17

Which of the following is a correct statement about acids?

Accepted Answer

Acids dissociate in water to release $	ext{H}^+$ ions

Question 18

Which of the following best describes the relationship between electronegativity and bond type?

Accepted Answer

Greater difference in electronegativity leads to polar covalent or ionic bonds

Question 19

Which of the following is NOT a property of compounds compared to their constituent elements?

Accepted Answer

Compounds have different properties than their constituent elements

Question 20

A molecule of methane ($	ext{CH}_4$) is formed by sharing electrons equally between carbon and hydrogen. What type of bond is present?

Accepted Answer

Non-polar covalent bond

Basic Chemistry for Biology: Elements, Compounds, and Trace Elements

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