Question 1

Which of the following best distinguishes an element from a compound?

Accepted Answer

An element is a substance that cannot be broken down into simpler substances by chemical means, while a compound consists of two or more elements chemically combined in fixed ratios.

Question 2

Which of the following is NOT a property that can be determined from a simplified atomic model?

Accepted Answer

Type of chemical bond formed with other atoms

Question 3

Given an atom with 11 protons, 12 neutrons, and 11 electrons, what is its atomic number and mass number?

Accepted Answer

Atomic number: 11, Mass number: 23

Question 4

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 5

A radioactive isotope of carbon, $$^{14}C$$, has 6 protons. How many neutrons does it have?

Accepted Answer

$$8$$

Question 6

Which of the following is a correct statement about electron shells and chemical reactivity?

Accepted Answer

Atoms with incomplete outer electron shells tend to be more chemically reactive.

Question 7

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of electrons between two atoms.

Question 8

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

Accepted Answer

The bond between hydrogen and oxygen in a water molecule ($$H_2O)$$

Question 9

Which of the following best explains why water is a good solvent for ionic compounds?

Accepted Answer

Water is a polar molecule, so it can surround and separate ions due to its partial charges.

Question 10

Which of the following statements about hydrogen bonds is correct?

Accepted Answer

Hydrogen bonds are weak attractions between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Question 11

Which of the following best distinguishes between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve the transfer of electrons, while covalent bonds involve the sharing of electrons.

Question 12

A molecule of $$NaCl is $$formed when:

Accepted Answer

A sodium atom transfers an electron to a chlorine atom, forming oppositely charged ions that attract each other.

Question 13

Which of the following is a real-life example of the importance of hydrogen bonding?

Accepted Answer

Hydrogen bonds between water molecules give water its high surface tension and boiling point.

Question 14

Which of the following best describes the relationship between atomic number and the identity of an element?

Accepted Answer

The atomic number is equal to the number of protons in the nucleus, which determines the element.

Question 15

Which of the following best explains why isotopes of the same element have different atomic masses?

Accepted Answer

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

Question 16

Which of the following is a correct statement about the formation of molecules?

Accepted Answer

Molecules are formed when two or more atoms are held together by chemical bonds.

Question 17

Which of the following best describes a nonpolar covalent bond?

Accepted Answer

A bond in which electrons are shared equally between two atoms.

Question 18

Which of the following is a correct comparison between hydrogen bonds and ionic bonds?

Accepted Answer

Hydrogen bonds are weaker than ionic bonds and do not involve the transfer of electrons.

Chapter 2 - bio 1201

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