115. Calculate the mass of each of the following amounts. a. 3.00 mol of selenium oxybromide, SeoBr2
b. 488 mol of calcium carbonate, CaCO3
c. 0.0091 mol of retinoic acid, C20H2O2
d. 6.00 x 10-8 mol of nicotine, C10H14N2
e. 2.50 mol of strontium nitrate, Sr(NO3)2
f. 3.50 x 10-6 mol of uranium hexafluoride, UF6

While unproven, it uses facts to support part of a conclusion. it is still factual and has predictive power, however.

Density= mass/volume so 5.1 divided by 4.7 is  5.1 / 4.7 =1.08510638298round to the correct number of sig figs

The population of unionid mussels decreased after zebra mussels were introduced. zebra mussels competed with the unionid mussels for food. the zebra mussels were able to displace the unionid mussels, allowing the zebra mussel population to increase  over the years. the unionid mussel population decreased because  of lack of food.

Radon-222 or rn-222 has a half-life of 3.82 days. to determine the fraction of an original sample of rn-222 that remains unchanged after 7.646 days, we calculate the amount of rn-222 remaining after 7.646 days and divide it with the original amount. using 1 gram as a basis and using half-life calculation methods, we can determine that  0.249 or 0.25  grams of rn-222 will remain, and thus the fraction remaining is 0.25 or 1/4.