Which of the following statements best describes the relationship between any point on an ellipse and each of its two foci?
A. The quotient of the distances to each focus equals a certain
constant.
B. The product of the distances to each focus equals a certain
constant.
C. The sum of the distances to each focus equals a certain constant.
D. The difference of the distances to each focus equals a certain
constant.

For a research project, a student decided to test the effect of the lead(ii) ion (pb2+) on the ability of salmon eggs to hatch. this ion was obtainable from the water‐soluble salt, lead(ii) nitrate, which the student decided to make by the following reaction. pbo(s) + 2 hno3(aq) → pb(no3)2(aq) + h2o losses of product for various reasons were expected, and a yield of 86.0% was expected. in order to have 5.00 g of product at this yield, how many grams of pbo should be reacted? (assume that sufficient nitric acid, hno3, would be used.)