Allotropes and Isotopes

     

    1) Which of the following is(are) allotropes of oxygen?

(a) O-17

(b) ozone

(c) dioxygen (O2)

(d) water

(e) air

 

    2) Chlorine has two naturally occurring isotopes, 35Cl and 37Cl, with masses of 34.9689 u and 36.9659 u, respectively. Calculate the abundances of these isotopes.

(a) 50.0%/50.0%

(b) 75.8%/24.2%

(c) 90.2%/9.8%

(d) 20.6%/79.4%

(e) 68.3%/31.7%

 

    3) Which of the following is(are) allotrope of oxygen?

(a) graphite

(b) C-13

(c) carbon tetrachloride

(d) diamond

(e) buckminsterfullerene (bucky balls)

 

    4) Bromine has two naturally occurring isotopes, 79Br and 81Br, with masses of 78.9183 u and 80.9163 u, respectively. Calculate the abundances of these isotopes.

(a) 32.6%/67.4%

(b) 74.5%/25.5%

(c) 29.3%/70.7%

(d) 50.7%/49.3%

(e) 38.2%/61.8%

 

    5) Which of the following is(are) allotrope of phosphorus?

(a) P-31

(b) white phosphorus

(c) red phosphorus

(d) phosphorus pentachloride

(e) black phosphorus

 

    6) Silver has two naturally occurring isotopes, 107Ag and 109Ag, with masses of 106.9051 u and 108.9048 u, respectively. Calculate the abundances of these two isotopes.

(a) 32.8%/67.2%

(b) 51.8%/48.2%

(c) 20.6%/79.4%

(d) 64.7%/35.3%

(e) 82.5%/17.5%

 

    7) Which of the following is(are) allotrope of sulfur?

(a) sulfur dioxide

(b) yellow sulfur

(c) S-34

(d) sulfuric acid

(e) sulfur monoxide

 

    8) Suppose you are trying to construct a periodic table in an parallel universe. You discover element "X", which has two isotopes. Isotope #1 has a mass of 39.96 u and an abundance of 74.2%. Isotope #2 has a mass of 40.96 u. What atomic mass would you put on the periodic table for element "X"?

(a) 40.22

(b) 40.46

(c) 39.96

(d) 40.96

(e) 70.61

 

 

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