$$\text{Number of neutrons} = \text{Atomic mass} - \text{Atomic number}$$

Question 1

Which of the following best describes the concept of mimicry as discussed in the context of butterfly wings?

Accepted Answer

A butterfly evolving colors that resemble poisonous species to avoid predation.

Question 2

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

Accepted Answer

Gold

Question 3

An atom of sulfur has an atomic number of 16 and an atomic mass of 34. How many neutrons does it have?

Accepted Answer

$$34 - 16 = 18$$ neutrons

Question 4

Which statement about protons is correct?

Accepted Answer

Protons have a positive charge and are found in the nucleus.

Question 5

What is the atomic number of chlorine?

Accepted Answer

$$17$$

Question 6

Which of the following best explains why oxygen atoms form double covalent bonds in $$O_2$$ molecules?

Accepted Answer

Each oxygen atom needs to share two pairs of electrons to fill its valence shell.

Question 7

If an atom is neutral, which of the following must be true?

Accepted Answer

The number of protons equals the number of electrons.

Question 8

Which of the following is a correct definition of an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 9

A molecule of hydrogen ($$H_2) is $$held together by which type of bond?

Accepted Answer

Nonpolar covalent bond

Question 10

Which of the following best describes a valence electron?

Accepted Answer

An electron found in the outermost energy shell of an atom.

Question 11

What is the difference in electronegativity between carbon and hydrogen? ($$	ext{C} = 2.5$$, $$	ext{H} = 2.1)$$

Accepted Answer

$$2.5 - 2.1 = 0.4$$

Question 12

Which of the following statements about covalent bonds is TRUE?

Accepted Answer

Covalent bonds involve the sharing of electrons between atoms.

Question 13

If the difference in electronegativity between two atoms is less than $$0.5$$, what type of bond will they form?

Accepted Answer

Nonpolar covalent bond

Question 14

Which of the following is the correct formula for calculating the number of neutrons in an atom?

Accepted Answer

$$	ext{Number of neutrons} = 	ext{Atomic mass} - 	ext{Atomic number}$$

Question 15

Which of the following best explains why valence electrons are important in chemical bonding?

Accepted Answer

They are involved in forming chemical bonds with other atoms.

Question 16

A molecule of nitrogen ($$N_2) $$contains a triple covalent bond. How many pairs of electrons are shared between the two nitrogen atoms?

Accepted Answer

Three pairs

Question 17

Which of the following statements about elements is correct?

Accepted Answer

Elements are substances that cannot be broken down into simpler substances by chemical processes.

Question 18

Which orbital is closest to the nucleus in an atom?

Accepted Answer

1s orbital

Question 19

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

Accepted Answer

$$8 + 8 = 16$$

Question 20

Which of the following is a real-world example of a nonpolar covalent bond?

Accepted Answer

The bond between two hydrogen atoms in $$H_2$$

Atoms, Elements, and Chemical Bonds: Foundations of General Biology

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