1. The process by which a solid changes into its liquid state at a certain fixed temperature by the absorption of heat is called _______.   fusion   solidification   vaporization   liquefaction   Hint Half-n-half Clue   2. If the specific latent heat of vaporization for water is 2.25 kJ/g, then the amount of heat required to vaporize 8 g of boiling water to steam at 100oC is   18 J   180 J   1800 J   18000 J   Half-n-half Clue   3. An increase in pressure results in an increase in the freezing point of a substance.   True   False   4. Water vapor is invisible.   True   False   5. When the cooling curve for naphthalene is plotted on a graph of temperature (in oC) vs. time (in minutes), the following three regions are observed: in the first 2 minutes, the temperature drops from 90oC to 80oC; in the next 6 minutes, the temperature remains constant at 80oC; and in the last 4 minutes, the temperature falls from 80oC to 60oC. The naphthalene is a liquid in the time interval from _______.   8 to 12 minutes   2 to 8 minutes   0 to 2 minutes   Half-n-half Clue   6. If 2925 J of energy are expended to rub two ice blocks against each other and the specific latent heat of ice is 325 J/g, then the mass of the melted ice is   9 g   18 g   27 g   36 g   Half-n-half Clue   7. In an experiment, a thin copper wire with weights at either end is placed on a supported block of ice. The thin wire is observed to cut through the ice. The phenomenon where the ice above the wire refreezes is called _______.   sublimation   subtraction   regelation   regeneration   Half-n-half Clue