CHEM 121 EXAM 1 (updated 2026) Questions &
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Terms in this set (90)
Which one of the following is the b. 2.5 g (convert all to same unit)
largest mass?
a. 2 x 10^-4 kg
b. 2 x 10^3 mg
c. 2 x 10^5 ng
d. 2 x 10^-2 g
e. 2 x 10^4 ug
How many moles of carbon would b. First calculate how many moles of C3H8 there
be found in 52.4 g C3H8 are (1.19 moles). Then multiply by molar ratio (3 mol
C/1 mol propane) = 3.57 mol C
,Which of the following is a postulate a. Atoms combine in whole number ratios to form
of Dalton's atomic theory? compounds
a. Atoms combine in whole number
ratios to form compounds
b. Atoms contain a tiny dense
nucleus
c. Protons are found in the nucleus
of an atom
d. The number of neutrons in an atom
determines the identity of the
element
e. Atoms contain electrons.
The density of an unknown c. multiply 98.3 g by (1 cm3/8.76 g) to make 11.2
substance is 8.76 g/cm3. How many g/cm3
cm3 would a 98.3 g sample of this
substance occupy?
Which of the following statements is d. all of the atoms have the same number of
TRUE about these 3 atoms: 43/23 V neutrons
(this means Vanadium with a 43 on
upper left and 23 on lower left);
40/20 Ca^2+; 37/17 Cl^-
a. All of the atoms are isotopes of
one another
b. All of the atoms have the same
number of electrons
c. All of the atoms have the same
number of protons
d. All of the atoms have the same
number of neutrons
e. All of the atoms belong in the
fourth period
, How many significant figures are =8.9/3.242 = 2.7. Two sig figures. The subtraction
present in the following calculations part gives one decimal place after the decimal,
(SHOW WORK) (2 pts) because that was the level of uncertainty in the
(24.3 - 15.44) / 3.242 subtraction. That number thus as 2 sig digits.
4 NH3 + 7 O2 --> 4 NO2 + 6 H2O 5.82 mol NH3 ( 4 mol NO2/4 mol NH3) = 5.82;
If 5.82 moles of NH3 are reacted 9.74 mol O2 (4/7) = 5.57 mol NO2 so O2 is limiting
with 9.74 moles of oxygen gas, how and can only make 5.57 moles of NO2
many moles of NO2 will be formed?
Which reactant is limiting? (3 pts)
Balance, including the states of 2 Al (s) + 3 Br2 (l) --> 2 AlBr3 (g)
matter:
The reaction of solid aluminum with
liquid bromine to form solid
aluminum bromide (1 pts)
Balance, including the states of 3 Al(ClO4)3 (aq) + 3 Ba(OH)2 (aq) --> 3 Ba(ClO4)2
matter: (aq) + 2 AL(OH)3 (s)
Al(ClO4)3 (aq) + Ba(OH)2 (aq) -->
Ba(ClO4)2 (aq) + Al(OH)3 (g)
Balance, including the states of C5H10O + 7O2 --> 5 CO2 (g) + 5 H2O (g)
matter:
The combustion of C5 H10 O in
oxygen gas to corm carbon dioxide
gas and water vapor
Give an example of each of the Ca, Ar, Fe, Si
following: (.5 pts each)
a. Alkaline earth metal
b. noble gas
c. transition metal
d. metalloid
Answers | Latest Already Graded A+ UPDATE
Save
Terms in this set (90)
Which one of the following is the b. 2.5 g (convert all to same unit)
largest mass?
a. 2 x 10^-4 kg
b. 2 x 10^3 mg
c. 2 x 10^5 ng
d. 2 x 10^-2 g
e. 2 x 10^4 ug
How many moles of carbon would b. First calculate how many moles of C3H8 there
be found in 52.4 g C3H8 are (1.19 moles). Then multiply by molar ratio (3 mol
C/1 mol propane) = 3.57 mol C
,Which of the following is a postulate a. Atoms combine in whole number ratios to form
of Dalton's atomic theory? compounds
a. Atoms combine in whole number
ratios to form compounds
b. Atoms contain a tiny dense
nucleus
c. Protons are found in the nucleus
of an atom
d. The number of neutrons in an atom
determines the identity of the
element
e. Atoms contain electrons.
The density of an unknown c. multiply 98.3 g by (1 cm3/8.76 g) to make 11.2
substance is 8.76 g/cm3. How many g/cm3
cm3 would a 98.3 g sample of this
substance occupy?
Which of the following statements is d. all of the atoms have the same number of
TRUE about these 3 atoms: 43/23 V neutrons
(this means Vanadium with a 43 on
upper left and 23 on lower left);
40/20 Ca^2+; 37/17 Cl^-
a. All of the atoms are isotopes of
one another
b. All of the atoms have the same
number of electrons
c. All of the atoms have the same
number of protons
d. All of the atoms have the same
number of neutrons
e. All of the atoms belong in the
fourth period
, How many significant figures are =8.9/3.242 = 2.7. Two sig figures. The subtraction
present in the following calculations part gives one decimal place after the decimal,
(SHOW WORK) (2 pts) because that was the level of uncertainty in the
(24.3 - 15.44) / 3.242 subtraction. That number thus as 2 sig digits.
4 NH3 + 7 O2 --> 4 NO2 + 6 H2O 5.82 mol NH3 ( 4 mol NO2/4 mol NH3) = 5.82;
If 5.82 moles of NH3 are reacted 9.74 mol O2 (4/7) = 5.57 mol NO2 so O2 is limiting
with 9.74 moles of oxygen gas, how and can only make 5.57 moles of NO2
many moles of NO2 will be formed?
Which reactant is limiting? (3 pts)
Balance, including the states of 2 Al (s) + 3 Br2 (l) --> 2 AlBr3 (g)
matter:
The reaction of solid aluminum with
liquid bromine to form solid
aluminum bromide (1 pts)
Balance, including the states of 3 Al(ClO4)3 (aq) + 3 Ba(OH)2 (aq) --> 3 Ba(ClO4)2
matter: (aq) + 2 AL(OH)3 (s)
Al(ClO4)3 (aq) + Ba(OH)2 (aq) -->
Ba(ClO4)2 (aq) + Al(OH)3 (g)
Balance, including the states of C5H10O + 7O2 --> 5 CO2 (g) + 5 H2O (g)
matter:
The combustion of C5 H10 O in
oxygen gas to corm carbon dioxide
gas and water vapor
Give an example of each of the Ca, Ar, Fe, Si
following: (.5 pts each)
a. Alkaline earth metal
b. noble gas
c. transition metal
d. metalloid
