Cell Bio Ch.2 The Chemical Context of Life

Changing the number of __________ would change an atom into an atom of a different element. A. electrons circling the nucleus of an atom B. particles in the nucleus of an atom C. bonds formed by an atom D. protons in an atom E. neutrons in an atom

D. protons in an atom

3H2 + N2 ↔ 2NH3 Which of the following factors will increase the rate of reaction in the forward direction? A. addition of nitrogen B. addition of hydrogen C. addition of ammonia D. addition of both nitrogen and hydrogen

D. addition of both nitrogen and hydrogen

Which of the following types of bond is broken when water evaporates? A. ionic bonds B. nonpolar covalent bonds C. polar covalent bonds D. hydrogen bonds

D. hydrogen bonds

What does the term electron orbital describe? A. An electron orbital describes a three-dimensional space where an electron can be found 90% of the time. B. An electron orbital describes the orbit of an electron around the nucleus. C. An electron orbital describes the exact distance of an electron from the nucleus.

A. An electron orbital describes a three-dimensional space where an electron can be found 90% of the time.

Which of the following are compounds? A. H2O and CH4, but not O2 B. H2O, O2, and CH4 C. O2 and CH4 D. H2O and O2

A. H2O and CH4, but not O2

What happens when two atoms form a chemical bond? A. A chemical bond forms when two atoms transfer or share outer electrons to complete their outer shells. B. A chemical bond forms when two atoms transfer or share protons to achieve a stable nucleus. C. Two atoms fuse together to form a chemical bond.

A. A chemical bond forms when two atoms transfer or share outer electrons to complete their outer shells.

Which of the following bonds can form between atoms of equal electronegativity? A. Van der Waals interactions can form between atoms of equal electronegativity. B. Hydrogen bonds can form between atoms of equal electronegativity. C. Ionic bonds can form between atoms of equal electronegativity.

A. Van der Waals interactions can form between atoms of equal electronegativity.

Which of the following is a trace element found in the human body? A. magnesium B. nitrogen C. carbon D. hydrogen E. oxygen

A. magnesium

How many electrons are present in a H- and H+ ion respectively? A. 0,2 B. 2,0 C. 1,2 D. 2,1

B. 2,0

Which of the following is a true statement about how living organisms use energy and chemicals to carry out life's activities? A. Both energy and chemicals flow through an ecosystem. B. Energy flows through an ecosystem, but chemicals cycle within it. C. Energy cycles within an ecosystem, but chemicals flow through it. D. Both energy and chemicals cycle within an ecosystem.

B. Energy flows through an ecosystem, but chemicals cycle within it.

Which of the following statements is TRUE? A. Carbon, hydrogen, oxygen, and calcium are the most abundant elements of living matter. B. Some naturally occurring elements are toxic to organisms. C. A patient suffering from a goiter should not consume seafood. D. All life requires the same essential elements.

B. Some naturally occurring elements are toxic to organisms.

About 25 of the 92 natural elements are known to be essential to life. Four of these 25 elements make up approximately 96% of living matter. Which of the following elements account for most of the remaining 4% of an organism's mass? A. carbon, hydrogen, nitrogen, oxygen B. calcium, potassium, phosphorus, sulfur C. oxygen, hydrogen, calcium, nitrogen D. carbon, oxygen, hydrogen, nitrogen

B. calcium, potassium, phosphorus, sulfur

A substance that cannot be broken down into other substances by ordinary chemical procedures is a(n) __________. A. proton B. element C. compound D. isotope E. molecule

B. element

Which one of the following describes the correct trends in electronegativity in the periodic table? A. increases across a period and increases down a group B. increases across a period and decreases down a group C. decreases across a period and increases down a group D. decreases across a period and decreases down a group

B. increases across a period and decreases down a group

Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by all forms of life? A. iodine B. iron C. arsenic D. mercury

B. iron

A covalent bond is likely to be polar under which of the following conditions? A. the two atoms sharing electrons are equally electronegative B. one of the atoms sharing electrons is more electronegative than the other atom C. carbon is one of the two atoms sharing electrons D. the two atoms sharing electrons are of the same elements

B. one of the atoms sharing electrons is more electronegative than the other atom

Which of the following subatomic particles always has a positive charge? A. electron B. proton C. atom D. element E. neutron

B. proton

A salamander relies on hydrogen bonding to stick to various surfaces. Therefore, a salamander would have the greatest difficulty clinging to a ________. A. surface of mostly carbon-nitrogen bonds B. surface of hydrocarbons C. surface of mostly carbon-oxygen bonds D. slightly damp surface

B. surface of hydrocarbons

Which statement about relative potential energy of electrons is correct? A. An electron in the 2 p orbital of the second electron shell has more potential energy than an electron in the 3 p orbital of the third electron shell. B. An electron in the 2 p orbital of the second electron shell has more potential energy than an electron in the 2 s orbital of the second electron shell. C. An electron in the 3 p orbital of the third electron shell has more potential energy than an electron in the 2 p orbital of the second electron shell.

C. An electron in the 3 p orbital of the third electron shell has more potential energy than an electron in the 2 p orbital of the second electron shell.

Which statement about weak bonds is correct? A. Weak bonds are less important to living things than strong covalent bonds. B. Weak chemical bonds form only between atoms of similar electronegativity. C. Weak bonds are transient and easily reversible.

C. Weak bonds are transient and easily reversible.

Van der Waals interactions may result under which of the following conditions? A. molecules held by ionic bonds react with water B. two polar covalent bonds react C. electrons are not symmetrically distributed in a molecule D. a hydrogen atom loses an electron

C. electrons are not symmetrically distributed in a molecule

An atom has four electrons in its valence shell. What types of covalent bonds is it capable of forming? A. single and double only B. single bonds only C. single, double, or triple D. double bonds only

C. single, double, or triple

Hydrogen bonding is most often seen __________. A. when multiple carbon atoms are present B. if the molecule consists of three or fewer atoms C. when hydrogen is covalently bonded to an electronegative atom D. when the molecule's three-dimensional shape is tetrahedral E. when the bonds within the molecule are nonpolar covalent bonds

C. when hydrogen is covalently bonded to an electronegative atom

Under which of the following conditions will an atom be the most stable? A. when they have the fewest possible valence electrons B. when all electrons are paired C. when they have the maximum number of unpaired electrons D. when all of the electron orbitals in the valence shell are filled

D. when all of the electron orbitals in the valence shell are filled

The atoms of different phosphorus isotopes _____. A. have different numbers of electrons B. have different atomic numbers C. react differently with other atoms D. have different numbers of protons E. have different numbers of neutrons

E. have different numbers of neutrons