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

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

Question 1

Which of the following statements best describes the relationship between atoms, elements, and molecules?

Accepted Answer

Atoms are the fundamental units that combine to form molecules; elements are substances made of only one type of atom.

Question 2

Carbon-12 and Carbon-14 are examples of:

Accepted Answer

Isotopes, because they have the same number of protons but different numbers of neutrons.

Question 3

Which of the following best explains why water is considered an excellent solvent?

Accepted Answer

Water's polarity allows it to surround and separate charged and polar molecules.

Question 4

An atom of oxygen has 8 protons, 8 neutrons, and 10 electrons. What is the charge of this atom?

Accepted Answer

Negatively charged, because it has more electrons than protons.

Question 5

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

Accepted Answer

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

Question 6

Which property of water is most directly responsible for the ability of some insects to walk on its surface?

Accepted Answer

Water's cohesion due to hydrogen bonding.

Question 7

If sodium (Na) loses one electron, what is the resulting charge and what is this particle called?

Accepted Answer

Positive; it is called a cation.

Question 8

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of electrons between atoms.

Question 9

Which of the following ions is most important for nerve impulse transmission in biological systems?

Accepted Answer

$$	ext{Na}^{+}$$

Question 10

A radioactive isotope of carbon, Carbon-14, is used in medical imaging. What property makes it useful for this purpose?

Accepted Answer

It emits radiation that can be traced in biological systems.

Question 11

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same column have the same number of valence electrons.

Question 12

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

Accepted Answer

They allow for the transformation and transfer of energy necessary for life.

Question 13

Which of the following is NOT a bulk element required for life?

Accepted Answer

Iron

Question 14

If an atom has 6 protons, 6 neutrons, and 6 electrons, what element is it and what is its atomic number?

Accepted Answer

Carbon; atomic number 6

Question 15

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

Accepted Answer

Buffers maintain pH stability by neutralizing acids and bases.

Question 16

Which equation correctly represents the relationship between the number of protons ($$p$$), neutrons ($$n$$), and electrons ($$e) in a $$neutral atom?

Accepted Answer

$$p = e$$

Question 17

Which of the following scenarios best illustrates the formation of an ionic bond?

Accepted Answer

One atom donates an electron to another, resulting in oppositely charged ions that attract each other.

Question 18

Which property of water allows it to moderate temperature changes in living organisms?

Accepted Answer

High specific heat

Question 19

Which of the following is a correct statement about isotopes?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 20

A scientist is using a radioactive isotope as a biological tracer. Which property of the isotope is most important for this application?

Accepted Answer

It emits detectable radiation as it decays.

The Chemical Foundations of Life: Atoms, Elements, and Water in Biology

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