Question 1

Which statement best explains the concept of emergent properties in compounds, as illustrated by the formation of sodium chloride (NaCl) from sodium and chlorine?

Accepted Answer

Emergent properties are the new characteristics that arise when elements combine to form compounds, which are different from the properties of the individual elements.

Question 2

Which of the following best describes an element?

Accepted Answer

A substance that cannot be broken down into other substances by chemical reactions.

Question 3

Given the atomic number ($$Z) $$and mass number ($$A) of an $$atom, which formula correctly calculates the number of neutrons ($$N) in $$the atom?

Accepted Answer

$$N = A - Z$$

Question 4

Which of the following elements makes up the largest percentage of body mass in humans?

Accepted Answer

Oxygen

Question 5

A radioactive isotope of carbon has a mass number of 14. How many neutrons does it have?

Accepted Answer

8

Question 6

Which of the following best describes a covalent bond?

Accepted Answer

The sharing of a pair of valence electrons between two atoms.

Question 7

What is the main reason noble gases are chemically inert?

Accepted Answer

They have a full valence electron shell.

Question 8

Which type of chemical bond is responsible for the partial positive and negative charges in a water molecule?

Accepted Answer

Polar covalent bond

Question 9

A sodium atom ($$Na) $$loses one electron to become a sodium ion ($$Na^+). $$What type of ion is $$Na^+$$?

Accepted Answer

Cation

Question 10

Which of the following best describes a hydrogen bond?

Accepted Answer

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

Question 11

Which statement about chemical reactions is correct?

Accepted Answer

Chemical reactions involve the making and breaking of chemical bonds.

Question 12

Photosynthesis is represented by the following equation: $$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2. $$What are the reactants in this reaction?

Accepted Answer

$$CO_2$$ and $$H_2O$$

Question 13

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

Accepted Answer

Iron

Question 14

If an atom has 7 protons, 8 neutrons, and 7 electrons, what is its atomic mass?

Accepted Answer

$$15$$

Question 15

Which of the following interactions is responsible for the ability of a gecko to climb smooth surfaces?

Accepted Answer

Van der Waals interactions

Question 16

What determines the chemical behavior of an atom?

Accepted Answer

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

Question 17

Which of the following best describes chemical equilibrium in a reaction?

Accepted Answer

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

Question 18

Which of the following is true about ionic compounds such as sodium chloride ($$NaCl$$)?

Accepted Answer

$$NaCl$$ forms crystals and dissociates easily in water.

Question 19

Which of the following best explains why morphine and endorphins can bind to the same brain receptors?

Accepted Answer

They have similar molecular shapes due to the positions of their atoms' orbitals.

Question 20

Which of the following statements about electron orbitals is correct?

Accepted Answer

An orbital is the three-dimensional space where an electron is found 90% of the time.

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

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