chemistry hard core, it’s just hard….

 


2. The common isotopes of carbon are 12C and 13C. The average mass of carbon is 12.01115 amu. What is the abundance of the 13C isotope?
(a) 1.115%
(b) 98.885%
(c) 0.480%
(d) 99.52%
3. If the abundance of 6Li (6.015121 amu) is 7.500% and the abundance of 7Li (7.016003 amu) is 92.500%, what is the average atomic mass?
(a) 6.0750 amu
(b) 6.0902 amu
(c) 6.9250 amu
(d) 6.9409 amu
4. What do the following have in common?

20Ne  19F  24Mg2+

(a) They are isotopes of each other.
(b) They are isomers of each other.
(c) They are isoelectronic with each other.
(d) They are different elements so they have nothing in common.
5. How many valence electrons does an oxygen atom have?
(a) 2
(b) 6
(c) 8
(d) 16
6. Fluorine atoms tend to…?…when they form chemical compounds with metals.
(a) lose electrons
(b) gain electrons
(c) neither lose nor gain electrons…they usually share electrons equally with metals.
(d) Fluorine atoms do not form compounds with other atoms…fluorine is an inert gas.
7. The identity of an element is determined by…
(a) the number of its protons.
(b) the number of its neutrons.
(c) the number of its electrons.
(d) its atomic mass.

9. Which of the following electron configurations represents the electron configuration for a magnesium cation…Mg2+?
(a) 1s22s22p63s2
(b) 1s22s22p63s23p2
(c) 1s22s22p6
(d) 1s22s22p4

11. The half-life of francium-212 is 19 minutes. How many minutes will it take for 1 gram of this isotope to decay to 0.125 grams?
(a) 4.75 minutes
(b) 9.5 minutes
(c) 38 minutes
(d) 57 minutes
12. The atom formed by the beta decay of carbon-14 is…
(a) oxygen-18
(b) beryllium-10
(c) boron-14
(d) nitrogen-14

 
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