2. (9) Mercury is the only common metal liquid at ordinary temperatures. Calculate the density of mercury (in g/cm) if 162 g of the substance occupies 12.0 cm'. 3. (7) Convert 29.76 C, the melting point of gallium, to kelvin (K). 4. (13) Potassium (density = 890 kg/m) is the seventh most abundant element and makes up about 2.4% by weight of the Earth's crust. What is its density in g/cm? 5. (16) For each of the following species, determine the number of protons and the number of neutrons in the nucleus: a. H b. 282H8 c. 80 149 d. He 27 e. 23A1 f. 52Cr 24 g. K h. 21 Pu