CHEM121 EXAM 1 QUESTIONS
AND CORRECT ANSWERS
N subscript O
6.022 x 10^23 mol^-1
Which of the following formulas has the greatest
number of atoms of any type per formula unit?
a) Pb(C2H3O2)2
b) Ca(PO4)3(OH)
c) (NH4)Cr207
d) Al2(SO3)3
e) CaS04 *2 H2O
b) Ca(PO4)3(OH): 20 atoms
Which of the following series of elemental symbols
lists a halogen, an alkaline earth metal and a metalloid
(in no particular order)?
a) Ge, Br, Ba
b) Mg, B, K
c) Cu, Ca, O
d) O, Na, S
e) Ag, As, Cr
a) Ge, Br, Ba
Ge: metalloid
Br: halogen
Ba: alkaline earth metal
, When the following reaction is properly balanced,
what is the coefficient in front of H2S
FeC13(aq) + H2S(g) —> Fe2S3(s) + HCl(aq)
c) 3
Three students (I, Il, and Ill) are asked to determine the
volume of a sample of ethanol. Each student
measures the volume three times with a graduated
cylinder. The results are as follows:
Student l: 55.5 mL ; 58.2 ml ; 53.2 mL
Student Il: 56.7 ml ; 56.8 ml ; 56.8 ml
Student Ill: 55.6 ml ; 55.6 ml ; 54.1 ml
The"true" volume is 55.6 mL. The student with the
greatest precision was (blank)
; and the student with the greatest accuracy was
(blank)
d) II ; I
Which of the following statements is not correct based
on the Law of definite Proportions?
a) All samples of sodium chloride have the same
composition, no matter the source.
b) No matter where a sodium chloride sample comes
from, it will always have the same percentages of each
element.
c) The amount of sodium that will combine with one
gram of chlorine to form sodium chloride is a fixed
AND CORRECT ANSWERS
N subscript O
6.022 x 10^23 mol^-1
Which of the following formulas has the greatest
number of atoms of any type per formula unit?
a) Pb(C2H3O2)2
b) Ca(PO4)3(OH)
c) (NH4)Cr207
d) Al2(SO3)3
e) CaS04 *2 H2O
b) Ca(PO4)3(OH): 20 atoms
Which of the following series of elemental symbols
lists a halogen, an alkaline earth metal and a metalloid
(in no particular order)?
a) Ge, Br, Ba
b) Mg, B, K
c) Cu, Ca, O
d) O, Na, S
e) Ag, As, Cr
a) Ge, Br, Ba
Ge: metalloid
Br: halogen
Ba: alkaline earth metal
, When the following reaction is properly balanced,
what is the coefficient in front of H2S
FeC13(aq) + H2S(g) —> Fe2S3(s) + HCl(aq)
c) 3
Three students (I, Il, and Ill) are asked to determine the
volume of a sample of ethanol. Each student
measures the volume three times with a graduated
cylinder. The results are as follows:
Student l: 55.5 mL ; 58.2 ml ; 53.2 mL
Student Il: 56.7 ml ; 56.8 ml ; 56.8 ml
Student Ill: 55.6 ml ; 55.6 ml ; 54.1 ml
The"true" volume is 55.6 mL. The student with the
greatest precision was (blank)
; and the student with the greatest accuracy was
(blank)
d) II ; I
Which of the following statements is not correct based
on the Law of definite Proportions?
a) All samples of sodium chloride have the same
composition, no matter the source.
b) No matter where a sodium chloride sample comes
from, it will always have the same percentages of each
element.
c) The amount of sodium that will combine with one
gram of chlorine to form sodium chloride is a fixed
