Jana is a chemist who is making a chemical to add to swimming pools in order to make the water safer. She mixed two solid substances together in a sealed container. The diagram above shows the repeating groups of atoms that make up the two starting substances. After mixing, Jana found two liquid substances in the sealed container. (Nothing had escaped.) Which of the diagrams below shows the repeating groups of atoms that make up the ending substances?

Alex measured the length of an item to be 3.7 cm. the actual length is 3.5 cm. what is alex’s percent error?

The actual length of side y is 22 cm. use the scale drawing to find the actual length of side x. a) 15.2 cm b) 17.1 cm c) 18.0 cm d) 28.3 cm

The biologist has a second culture to examine. she knows that the population of the culture doubles every 15 minutes. after 1 hour and 15 minutes, her assistant found that 80,000 bacteria were present. a) what was the size of the initial population? b) predict the size of the culture at t=3 hours. what was the size of the population at 40 minutes? explain and justify your answers. c) create a graph of the population as a function of time. find an equation that can be used to predict the size of the population at any time t. d) examine the rate at which the bacteria culture is growing. how fast is the culture growing after 1 hour? after 1.5 hours? after 2 hours? use a time interval of h = 0.01 hours to estimate these rates. interpret these rates in terms of the context of the problem situation. how do these three rates compare?