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Chemistry 121
Practice problem – EXAM 1
Dang
It is your responsibility to study all other materials
Question I
- Multiple choices: Please choose one best answer for each question.
1. Which of the following underlined items is not an intensive property?
A) A chemical reaction requires 3.00 g of oxygen.
B) Solid copper hydroxide is blue colored.
C) The density of helium at 25°C is 1.64 × 10-4 g/cm3.
D) The melting point of aluminum metal is 933 K
2. Which one of the following statements about temperature scales is false?
A) The boiling point of water on the Fahrenheit scale is 212 degrees.
B) The Celsius degree is smaller than the Fahrenheit degree.
C) The freezing point of water on the Celsius scale is 0 degrees.
D) All temperatures on the Kelvin scale are positive numbers.
3. Most of the alpha particles directed at a thin gold foil in Rutherford's experiment
A) bounced directly back from the foil.
B) passed directly through the foil undeflected.
C) passed through the foil but were deflected at an angle.
D) were absorbed by the foil.
4. Which are isotopes? An atom that has an atomic number of 34 and a mass number of 76 is an
isotope of an atom that has
A) an atomic number of 32 and a mass number of 76.
B) an atomic number of 34 and a mass number of 80.
C) 42 neutrons and 34 protons.
D) 42 protons and 34 neutrons.
5. Which one of the following statements about balanced equations is true? A reaction is balanced by
A) changing the charge on an ion.
B) changing the formula of the molecule.
C) multiplying by suitable coefficients.
D) rearranging atoms in a molecule.
10.
Which statement about elemental analysis by combustion is not correct?
A) Only carbon and hydrogen can be determined directly from CO2 and H2O.
B) Carbon is determined from the amount of CO2 formed.
C) Hydrogen is determined from the amount of H2O formed.
D) Oxygen is determined from the amount of H2O formed.
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Question II
A. Give a correct name for the following compounds
a. Hg2CrO4
b.
NaH2PO4
b.
Dinitrogen pentoxide
b.
Sn2+ and BrO3-
B. Give a correct formula for the following molecules
a.
Tetraphosphorous decasulfide
C. Write the formula for the following ions
a. Fe2+ and HSO4-
D.
Balance the following equations
_____ CO2(g) + _____ KOH(aq) → _____ K2CO3(aq) + _____ H2O(l)
-------- CH4(g) + ……..Br2(g)  ………CBr4(aq) + …… HBr(aq)
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Question III
A. A lead atom has a mass of 3.4 x 10-22 g. How many lead atoms are in a cube of lead that has a volume of
2.00 cm3 if the density of lead is 11.3 g/cm3
6.5 x 1022
B. What mass of water is produced by the reaction of 50.0 g CH3OH with an excess of O2 when the yield is
53.2%
2CH3OH(g) + 3 O2(g)  2 CO2(g) + 4 H2O(l)
29.9 g H2O
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Question IV
Determine the empirical formula of an organic compound containing only C and H given that combustion of 1.50 g
sample of the compound produces 4.71 g CO2 and 1.93 g H2O
CH2
What is its molecular formula with the molecular mass of 28.06 g/mol
C2H4
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