1) A tick bird on a rhinosaurus is an example of what type of symbiotic relationship? A. Commensalism B. Mutualism C. Parasitism D. Saprophytism E. Insectism Answer key says 'B'. I am not an ecology person, but I put 'A' because commensalism means one organism gets a benefit while the other is neither harmed nor helped. In what way is a rhino benefiting from the 'tick bird'? Is that information something I would have had to know beforehand? 2) When 14.250 moles of PCl5 gas is placed in a 3.00 liter container and comes to equilibrium at a constant temperature, 40.0% of the PCl5 is decomposed PCl5 (g) ------------> PCl3 (g) + Cl2 (g) What is the value of Kc?? A. (1.896)^2 / (2.854) B. (2.854)^2 / (1.898) C. (3.800)^2 / (2.854) D. (2.854)(1.896) / (3.800) E. None of these The answer key says 'A'. I know that Kc is = to [PCl3][Cl2] / [PCl5], and that concentrations of PCl3 and Cl2 are equal, and that the concentrations should be measured in atms, but I cannot make the numbers work out. How do you figure out the pressures?? Thanks so much for whoever can help! Taking my DAT 3 weeks from today!!!