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Review Questions Chapter 4

1 Which particle has the smallest mass?

electron
proton
neutron
alpha particle
No answers are correct.

2. Which particle carries no charge?

electron
proton
neutron
alpha particle
No answers are correct.

3. Which particles are found in the nucleus of an atom?

electrons and protons
electrons and neutrons
electrons and alpha particles
protons and neutrons
protons and alpha particles

4. Uranium exists as many isotopes, one of which is . Which of the following might also be isotopes of uranium?

atoms with atomic number 92 and mass number 239, 241, and 227
atoms with atomic number 92, mass number 239 and atomic number 91, mass number 235, and atomic number 93, mass number 237
atoms with atomic number 91, mass number 235 and atomic number 93, mass number 237
none
atoms with atomic number 91, mass number 235

5. Rutherford's experiment is diagrammed below. Which path is followed by most of the alpha particles that hit the gold foil?

Al
B
 C
D
E

6. Why is Rutherford's gold-foil experiment so important in the history of atomic structure?

It showed that gold can be hammered into a thin foil only a few atoms thick
It showed that atoms are composed of protons, electrons, and neutrons.
It showed that alpha particles have a relative charge of +2.
It showed that most of the atom was empty space surrounding a tiny, dense nucleus.
It showed that particles with like charges repel each other

7. The atomic weight of galium is 69.72. It occurs as gallium-69 and gallium-71. What is the approximate percent of gallium-69 in naturally occurring gallium?

10%
40%
50%
60%
90%

8. A sample of iron weighs 6.93 grams. How many moles of iron are contained in this sample?

8.06 mol
0.0806 mol
0.124 mol
0.0546 mol
0.365 mol

9. What is the mass of 1.55x10-2 mol copper?

9.85 g
0.985 g
91.3 g
0.931 g
none of these

10. A sample of lead contains 3.01 x 1021 atoms. A sample of another metal contains the same number of atoms and weighs 1.01 g. What might the second metal be?

nickel
tin
iron
platinum
mercury

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