exam 2 bio 181
What is the OH- concentration of a solution having a pH of 2 ?
1 × 10 - 12
What is the atomic mass of the atom identified as letter A in the accompanying figure ? The embedded figure contains two electron distribution diagrams , lettered A and B. Letter A is an electron shell distribution diagram with six protons , 6 neutrons , and 6 electrons .
12 amu
What is the atomic mass of carbon ? The embedded figure is the periodic table from our textbook . It has call out images of the different biological elements and showing their atomic number , chemical name , number of electrons in each energy level , Bohr models , and atomic mass unites . The information provided for carbon is the letter C , the number 6 , the word carbon , number 2 and 4 , and at . mass of 12.01 amu .
12.01 amu
Sulfur has six valence electrons How many covalent bonds does a sulfur atom typically form
2
A chlorine atom has 17 protons and 18 neutrons . What is its atomic mass ?
35 amu
How many molecules are present in one mole of C6H12O6 ?
6.02 x 1023 molecules
Which statement best describes an atom ?
A substance that cannot be broken into a simpler substance
What is the difference between an electrically neutral atom and an ion ?
An ion has an unequal number of protons and electrons , while a neutral atom has an equal number .
What differentiates an organic compound from an inorganic compound ?
An organic compound contains carbon .
. arrangement A chemical formula shows the types and numbers of atoms in a molecule and their arrangement
False
Which substance is a reactant in the following chemical equation ? CO2 + H₂O → H₂CO3
H₂O
Which statement best describes the product of a chemical reaction ?
It is the substance generated by the reaction
As water boils and turns to steam , what happens to the hydrogen bonds ?
The hydrogen bonds break
Which statement about van der Waal interactions is false ?
They are very strong .
A HCI ( hydrochloric acid ) solution with a pH 3 has a lower [ OH- ] than [ H + ] .
True
An atom that has a filled valence shell is stable and unreactive .
True
The tetrahedron shape of a methane molecule is the result of orbital hybridization .
True
The embedded figure contains two electron distribution diagrams , lettered A and B. Letter A is an electron shell distribution diagram with six protons , 6 neutrons , and 6 electrons . Letter B is an electron shell distribution diagram with six protons , 7 neutrons , and 6 electrons .
Two isotopes of the same element
When a small amount of hydrochloric acid ( HCI ) is added to a solution of Na₂HPO4 , the pH of the solution does not change markedly . The pH also does not change drastically when a small amount of sodium hydroxide ( NaOH ) is added to this same solution . Based on these observations , the compound Na₂HPO4 is :
acting as a buffer
A salt is a compound in which the hydrogen ion of ___ is replaced by some other cation .
an acid
How can we identify a particular element ?
by its number of protons
The covalent bond between a hydrogen atom and the oxygen atom in water is formed when :
hydrogen and oxygen share an electron pair
Consider the aquatic insects pictured in the accompanying figure ; the image is of two water strider insects " walking " on water . Which characteristic of water molecules directly contributes to their remarkable " water walking " success ?
hydrogen bonds
The cohesiveness between water molecules is due largely to
hydrogen bonds
Sugar dissolves readily in water because it is a ( n ) ___ substance .
hydrophilic
Match the type of bond or interaction with its description . -Strong attractive force resulting from the transfer of electrons between atoms -Strong attractive force resulting from the sharing of electrons between atoms -Very weak attractive force joining nonpolar molecules -Holds adjacent water molecules together
ionic bond covalent bond van der Waals interaction hydrogen bond
Which component becomes oxidized in the following chemical reaction ? 4 Fe +3 0₂2 Fe₂O3
iron
The chemical behavior of an atom is determined most directly by the :
number of valence electrons
Which component is the oxidizing agent in the following chemical reaction ? 4 Fe +3 0₂2 Fe₂O3
oxygen
Which atom would most likely be involved in an ionic bond ?
sodium
It takes one calorie of heat to raise the temperature of one gram of water by one degree Celsius . This is referred to as the ___ of water .
specific heat
The representation H - O - H is known as a ( n ) :
structural formula
Which event illustrates evaporative cooling ?
sweat evaporating from the skin
Nitrogen has five electrons in its valence shell . How many electrons does it need to gain to complete its valence shell ?
three
Water molecules have a strong tendency to stick to one another , a property known as
cohesion
