To 1.00 l of water was added 2.00 g of solid barium carbonate, baco3. after stirring, it was found that the solid did not dissolve completely.
a) calculate which mass of baco3 has dissolved.
b) check that at ph = 4 the added mass of barium carbonate would dissolve completely.
data: pkps (baco3) = 8.3; pka1 (h2co3) = 6.35; pka2 (h2co3) = 10.33; mr(ba) = 137.3; mr(c) = 12.0; mr(o) = 16.0

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.

here is table 2-2:

country

percent of eligible voters that voted

rank

united states

44.9%

138

canada

60.1%

107

costa rica

84.6%

14

hungary

66.9%

82

japan

57.0%

118

egypt

27.7%

159

south africa

85.5%

10

ans is no, the data set cannot be plotted as a single circle graph