1. There are two stable isotopes of supposium (Su). Su-191=190.9609 u(27.30%) Su-194=193.9633 u(72.70%) Compute the atomic mass of supposium.
a. 194.0 u

b. 193.1 u

c. 191.8 u

d. 190.9 u

e. 192.5 u

2. Which would not be found with a mass spectrometer.
a. the atomic mass of a single isotope of potassium

b. the number of stable isotopes of potassium

c.the mass of a proton

d. the number of protons in potassium

e. the relative abundance of two isotopes of potassium

3. How many protons, neutrons, and electrons are in 24 Mg2+?
a. 10 protons, 12 electrons, 24 neutrons

b. 12 protons, 10 electrons, 12 neutrons

c.12 protons, 12 electrons, 24 neutrons

d. 24 protons, 10 electrons, 12 neutrons

e. 12 protons, 12 electrons, 12 neutrons

4.The age of rocks is sometimes calculated from the measured excess of lead 206 atoms over the normal abundance. The uranium isotope U-238 decays to lead-206.What is the percent abundance of lead-206 if there aare 4.52 X 10^21 atoms of lead-206 in a 198 g sample of ore that is 2.58% lead?

a. 27.7

b. 0.0202

c. 4.70 x 10^-3

d. 30.4 e. 0.782

5. The average atomic mass of B is 10.80 u. Boron has only two stable froms 10
5 B(10.00 u) and 11
5 B (11.00 u). What is the natural percent abundance of B?
a. 1.0%

b. 20%

c. 75%

d. 3.8% e. 80%

6. 57.7 g Ni contains how many atoms?

a. 3.47x10^23

b.0.983

c. 1.24 x 10^24

d. 6.13x10^23 e. 5.92x10^23

7. What mass of magnesium is necessary to make 10.5 g of magnesium bromide if 1.04 g of magnesium makes 7.88 g of magnesium bromide?
a. 7.89 g

b. 1.39 g

c. 79.9 g

d. 3.66 g e. 1.58 g

8. How many atoms of lead are required to cover a 33.0 cm by 45.0 cm area witha sheet of lead that is 0.140 mm thick? The density of lead is 11.35 g/cm3.
a. 1.42x10^26
b. 2.29x10^25
c. 6.86x10^22
d. 2.29x10^26
e. 6.86X10^23

9. The natural abundance of calcium in the earth's crust is 3.4% by mass. How many calcium atoms are present in a 1.50 g sample of the earth's crust?
a. 7.7x10^22

b. 7.7x10^20

c. 3.1x 10^22

d.6.6x10^23

e. 5.1x10^20

10.Rubidium possesses two stable forms and has an average mass of 85.5. 85Rb has a mass of 84.9 and a percent abundance of 72.2%. What is the mass of the other form of Rb?
a. 85.7 u
b. 88.3 u
c. 86.1 u
d. 89.4 u
e. 87.1 u

11. Which is the more abundant isotope, CI-35 or CI37?
a. CI-17
b. CI-37
c. The two isotopes are equal in balance
d. CI-35
e. A third unstable isotope is more abundant

12. An element has 5 stable isotopes. The mass and percentage of each are:
69.9243 20.52%
71.9217 27.43%
72.9234 7.76%
73.9219 36.54%
75.9214 7.76%
The element is which of the following
a. Se b. Ge c. Ga d. As e. Zn

13. Lead-206 has a relative abundance of 23.6%. What sized block of lead (in cubic centimeters) will contain 8.34x10^21 atoms of lead-206? The density of lead is 11.35 is g/cm3.
a. 0.253
b. 0.0107
c. 1.07
d. 12.1
e. 0.330

14. When decomposed chemically, 73.0 grams of a sample of HCI produce 71.0 g of Cl2 and 2.0 g of H2, while 34.0 g of a sample of H2s produce 32.0g of S and 2.0g of H2. This is an example of the Law:
a. of Definate Proportions
b. E=mc^2
c. of multiple proportions
d. of Conservation of Mass
e. none of these