There are several things that can help scientists evaluate which category something belongs to. The similarity in features is one of them. If two skulls looked alike, they were probably species of the same evolutionary category. For example say humans and monkeys rather than humans and dogs.
Similarly fossils have helped scientists categorise species. Study of the chromosomes (in cases with available chromosomes) can help scientists figure out a lot about the subjects and categorise them.
So your answer would pretty much be 2.80 x 10^24. The picture is just the explanation and how you would get that answer.
An acid is an ionic compound that produces positive hydrogen ions when dissolved in water. Acids taste sour and turn blue litmus paper red. A base is an ionic compound that produces negative hydroxide ions when dissolved in water. Bases taste bitter and turn red litmus paper blue.
What is the solubility of barium chromate in parts per million?
*parts per million = Grams of Solute/grams of solution X 10^6 (which is ppm)
2.787 x 10^-3g/L x 1L/1000g x 10^6 = 0.02779, or 2.78 x 10^-2ppm
Answer in parts per million to three significant figures =2.78ppm
this is correct for the pearson mastering chemistry question
