Which of the following relations is in Third normal form (3NF)? Give sufficient reasoning if not in 3NF. (a) R(ABCD) F = {ACD → B; AC → D; D → C; AC → B} (b) R(ABCD) F = {AB → C; BCD → A; D → A; B → C} (c) R(ABCD) F = {AB → C; ABD → C; ABC → D; AC → D} (d) R(ABCD) F = {C → B; A → B; CD → A; BCD → A}

There is an area in idaho named craters of the moon where most of the ground is covered with basalt, adark gray, igneous rock with no visibl crystals. what can you infer about the geographical history of the area?

How does a catalyst increase the speed of a reaction? a. the catalyst eliminates the activated complex stage, allowing products to form immediately. b. the catalyst lowers the energy level of the reactants, making it easier for them to react. c. the catalyst makes it easier for the activated complex to form, lowering the activation energy. d. the catalyst raises the energy level of the products, making the reaction finish sooner. reset next

The comparison of the number of atoms in a copper coin the size of a penny with the number of people on earth is made to illustrate which of the following? a. that atoms are indivisible b. that atoms are very small c. that atoms are very large d. that in a copper penny, there is one atom for every person on earth