Question 1

``` About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living matter? A) carbon, sodium, hydrogen, nitrogen B) carbon, oxygen, phosphorus, hydrogen C) oxygen, hydrogen, calcium, nitrogen D) carbon, hydrogen, nitrogen, oxygen E) carbon, oxygen, nitrogen, calcium ```

Accepted Answer

D

Question 2

``` Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants? A) nitrogen B) calcium C) iodine D) sodium E) phosphorus ```

Accepted Answer

C

Question 3

Which of the following statements is false? A) Carbon, hydrogen, oxygen, and nitrogen are the most abundant elements of living matter. B) Some trace elements are very abundant on Earth. C) Virtually all organisms require the same elements in the same quantities. D) Iron is an example of an element needed by all organisms. E) Other than some trace elements, animals are mostly made up of the same elements as plants, in similar proportions.

Accepted Answer

C

Question 4

Which of the following statements is false? A) Carbon, hydrogen, oxygen, and nitrogen are the most abundant elements of living matter. B) Some trace elements are very abundant on Earth. C) Virtually all organisms require the same elements in the same quantities. D) Iron is an example of an element needed by all organisms. E) Other than some trace elements, animals are mostly made up of the same elements as plants, in similar proportions.

Accepted Answer

E

Question 5

Why is each element unique and different from other elements in chemical properties? A) Each element has a unique atomic mass. B) Each element has a unique atomic weight. C) Each element has a unique number of protons in its nucleus. D) Each element has a unique number of neutrons in its nucleus. E) Each element has different radioactive properties.

Accepted Answer

C

Question 6

Knowing just the atomic mass of an element allows inferences about which of the following? A) the chemical properties of the element B) the number of protons in the element C) the number of neutrons in the element D) the number of protons plus neutrons in the element E) both the number of protons and the chemical properties of the element

Accepted Answer

D

Question 7

In what way are elements in the same column of the periodic table the same? A) They have the same number of protons. B) They have the same number of neutrons. C) They have the same number of electrons. D) They have the same number of electrons in their valence shell. E) They have the same number of electron shells.

Accepted Answer

D

Question 8

``` Oxygen has an atomic number of 8 and a mass number of 16. Thus, what is the atomic mass of an oxygen atom? A) exactly 8 grams B) exactly 8 daltons C) approximately 16 grams D) approximately 16 daltons E) 24 amu (atomic mass units) ```

Accepted Answer

D

Question 9

The nucleus of a nitrogen atom contains 7 neutrons and 7 protons. Which of the following is a correct statement concerning nitrogen? A) The nitrogen atom has a mass number of approximately 7 daltons and an atomic mass of 14. B) The nitrogen atom has a mass number of approximately 14 daltons and an atomic mass of 7. C) The nitrogen atom has a mass number of 14 and an atomic mass of 7 grams. D) The nitrogen atom has a mass number of 7 and an atomic number of 14. E) The nitrogen atom has a mass number of 14 and an atomic mass of approximately 14 daltons.

Accepted Answer

E

Question 10

Molybdenum has an atomic number of 42. Several common isotopes exist, with mass numbers of 92, 94, 95, 96, 97, 98, and 100. Therefore, which of the following can be true? A) Molybdenum atoms can have between 50 and 58 neutrons. B) The isotopes of molybdenum have different electron configurations. C) The isotopes of molybdenum can have between 50 and 58 protons. D) The isotopes of molybdenum have between 50 and 58 neutrons and have different electron configurations. E) The isotopes of molybdenum have between 50 and 58 protons and have different electron configurations.

Accepted Answer

A

Question 11

Carbon-12 is the most common isotope of carbon, and has an atomic mass of 12 daltons. A mole of carbon in naturally occurring coal, however, weighs slightly more than 12 grams. Why? A) The atomic mass does not include the mass of electrons. B) Some carbon atoms in nature have an extra proton. C) Some carbon atoms in nature have more neutrons. D) Some carbon atoms in nature have a different valence electron distribution. E) Some carbon atoms in nature have undergone radioactive decay.

Accepted Answer

C

Question 12

The precise weight of a mole of some pure elements like silicon (Si) can vary slightly from the standard atomic mass, or even from sample to sample. Why? A) The element may undergo radioactive decay. B) The element may react with itself and gain or lose subatomic particles. C) The atoms of the element form chemical bonds with each other, and that changes the weight of the element. D) The element may have multiple stable isotopes, and the isotopic composition may vary from sample to sample. E) The amount of energy absorbed by the element affects the mass of its electrons, and thus the atomic mass can vary slightly.

Accepted Answer

D

Question 13

One difference between carbon-12 (12/6 C) is that carbon-14 (14/6 C) has A) two more protons than carbon-12. B) two more electrons than carbon-12. C) two more neutrons than carbon-12. D) two more protons and two more neutrons than carbon-12. E) two more electrons and two more neutrons than carbon-12.

Accepted Answer

C

Question 14

``` An atom has 6 electrons in its outer shell. How many unpaired electrons does it have? A) 0 B) 2 C) 4 D) 6 E) 2 or 4 ```

Accepted Answer

B

Question 15

``` The atomic number of nitrogen is 7. Nitrogen-15 is heavier than nitrogen-14 because the atomic nucleus of nitrogen-15 contains how many neutrons? A) 6 B) 7 C) 8 D) 12 E) 14 ```

Accepted Answer

C

Question 16

Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient energy, a possible result is that A) an electron may move to an electron shell farther away from the nucleus. B) an electron may move to an electron shell closer to the nucleus. C) the atom may become a radioactive isotope. D) the atom would become a positively charged ion, or cation, and become a radioactive isotope. E) the atom would become a negatively charged ion, or anion.

Accepted Answer

A

Question 17

The atomic number of neon is 10. Therefore, which of the following is most correct about an atom of neon? A) It has 8 electrons in its outer electron shell. B) It is inert. C) It has an atomic mass of 10 daltons. D) It has 8 electrons in its outer electron shell and it is inert. E) It has 8 electrons in its outer electron shell, it is inert, and it has an atomic mass of 10 daltons.

Accepted Answer

D

Question 18

From its atomic number of 15, it is possible to predict that the phosphorus atom has A) 15 neutrons. B) 15 protons. C) 15 electrons. D) 8 electrons in its outermost electron shell. E) 15 protons and 15 electrons.

Accepted Answer

E

Question 19

Atoms whose outer electron shells contain 8 electrons tend to A) form ions in aqueous solutions. B) form hydrogen bonds in aqueous solutions. C) be stable and chemically nonreactive, or inert. D) be gaseous at room temperature. E) be both chemically inert and gaseous at room temperature.

Accepted Answer

E

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