7 . C
Of the two ions Cl– and Ca+, Cl– has the same electron configuration as argon, a noble gas, and
therefore has all paired electrons.8 . B
Fe has 26 electrons, configured as listed.9 . E
An element is a substance that cannot be further broken down by chemical means.10 . A
A cation is an ionic species with a positive charge. An anion is an ionic species with a negative
charge.
11 . B
Inert gases, elements in Group 0 (or VIII) of the periodic table, contain a full octet of valence
electrons in their outermost shells; this makes these elements the least reactive.
12 . E
All atoms of a given element have the same numbers of protons.
13 . D
A calorimeter is an apparatus used to measure the heat released or absorbed by a reaction.
14 . B
A barometer is used to measure atmospheric pressure.
15 . C
A balance is used to measure weight.
16 . A
Centrifuges can spin at very high rotor speeds (e.g., 60,000 rpm) to sediment out particles in
suspension.
17 . A
The Gibbs free energy is the energy of a system available to do work. The change in Gibbs free