Question 1

Which of the following statements best describes a compound?

Accepted Answer

A substance consisting of two or more elements in a fixed ratio, with characteristics different from those of its elements.

Question 2

Which four elements make up approximately 96% of living matter?

Accepted Answer

Carbon, hydrogen, oxygen, and nitrogen

Question 3

An atom of sodium (Na) has 11 protons and 12 neutrons. What is its mass number?

Accepted Answer

$$23$$

Question 4

Which of the following best explains why radioactive isotopes are useful as tracers in medical imaging?

Accepted Answer

They have the same number of protons as stable isotopes but emit detectable particles and energy as they decay.

Question 5

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the transfer of electrons from one atom to another, resulting in oppositely charged ions that attract each other.

Question 6

Which of the following elements is most likely to form a cation in an ionic bond?

Accepted Answer

Sodium ($$\mathrm{Na})$$

Question 7

A molecule of water ($$\mathrm{H_2O}) is $$held together by which type of bond between the hydrogen and oxygen atoms?

Accepted Answer

Polar covalent bond

Question 8

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Question 9

Which statement about van der Waals interactions is correct?

Accepted Answer

They arise from transient local partial charges due to random movement of electrons.

Question 10

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

Accepted Answer

Molecular shape determines how molecules interact and function in biological systems.

Question 11

A patient is given a radioactive tracer containing $$^{18}\mathrm{F} ($$fluorine-18) to detect cancerous tissue. Which property of $$^{18}\mathrm{F}$$ makes it suitable for this purpose?

Accepted Answer

It emits radiation that can be detected as it decays, allowing visualization of metabolic activity.

Question 12

Which of the following is true regarding chemical equilibrium?

Accepted Answer

At equilibrium, the concentrations of reactants and products remain constant because the forward and reverse reactions occur at the same rate.

Question 13

Which of the following best describes electronegativity?

Accepted Answer

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

Question 14

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

Accepted Answer

The bond between hydrogen and oxygen in water ($$\mathrm{H_2O})$$

Question 15

A molecule has the formula $$\mathrm{C_6H_{12}O_6$}. $$Which of the following statements is true?

Accepted Answer

It contains 6 carbon, 12 hydrogen, and 6 oxygen atoms.

Question 16

Which of the following best explains why sodium chloride ($$\mathrm{NaCl}) $$forms a crystal lattice in solid form?

Accepted Answer

The electrostatic attraction between oppositely charged ions arranges them in a repeating three-dimensional pattern.

Question 17

Which of the following is a trace element required by humans in minute quantities?

Accepted Answer

Iron ($$\mathrm{Fe})$$

Question 18

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

Accepted Answer

Atomic number $$= 8$$, mass number $$= 16$$

Question 19

Which of the following best describes the difference between a molecule and a compound?

Accepted Answer

A molecule consists of two or more atoms held together by covalent bonds, while a compound consists of two or more different elements in a fixed ratio.

Question 20

Which of the following scenarios best illustrates the concept of chemical equilibrium?

Accepted Answer

In a closed container, the rate of water vaporizing equals the rate of condensation, so the amount of liquid water and vapor remains constant.

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

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