@X@user.full_name@X@ @GMU: When 10.52 g of aspirin was dissolved in 104.9 g of benzene, the freezing point was 275.7 K. What is the formula mass of this compound? The freezing point depression constant for benzene is 5.12 (°C*kg)/mol. The melting point and boiling points are 5.50°C and 80.10°C, respectively.

@X@user.full_name@X@ @GMU: Uranium -238 decays in a series of steps to Pb-206. When the material is very old, one can treat the kinetics as a decay directly to Pb and the ratio of these two can be treated as a measure of the age of a rock. A rock containing 238U and 206Pb was examined to determine its approximate age. The molar ratio of 206Pb to 238U was 0.2212. Assuming no lead was originally present and that all lead formed remained in the rock, what is the age of the rock (in years)? The half-life of 238U is 4.50e9 yr.

@X@user.full_name@X@ @GMU: The temperature of 11.95 g of Fe increased by 8.58°C when heated. How much heat did it absorb if the heat capacity of Fe is 25.100 J/°C×mol?

Who was the first Secretary of State? 

@X@user.full_name@X@ @GMU: For which species should the central atom have a hybridization of sp3?

@X@user.full_name@X@ @GMU: What is the molecular shape of AsCl5 ?

@X@user.full_name@X@ @GMU: A 27.70 mL sample of H2SeO4 was neutralized by exactly 34.90 mL of 0.1618M Ca(OH)2. What was the molarity of H2SeO4?H2SeO4(aq) + Ca(OH)2(aq) → CaSeO4(aq) + 2H2O(l)

@X@user.full_name@X@ @GMU: What is the atomic number of an element if the mass of one atom is 1.497e-23 g?

@X@user.full_name@X@ @GMU: What is -6.46 °F on the Celsius scale?

@X@user.full_name@X@ @GMU: The average speed of H2S molecules (atoms) was 654.2 m/s. What was the temperature of the gas?