What can be determined from examining the fossil record?

A.

when many life forms became extinct

B.

when many life forms first appeared on Earth

C.

when changes to the diversity of life forms occurred

D.

all of these

Enter the chemical formula of a binary molecular compound of hydrogen and a Group 6A element that can reasonably be expected to be less acidic in aqueous solution than H2Se, e. g. have a smaller Ka.

11. The pH of an aqueous solution changes from 4 to 3 when the hydrogen ion concentration in the solution is

One method to produce nitrogen in the lab is to react ammonia with copper (II) oxide: NH3 ( g. + CuO (s) Cu (s) + H2O (l) + N2 ( g. After using 40.0 grams of NH3, 15.5 grams of N2 are produced. What is the percent yield of nitrogen in the reaction?

Lab Investigator: Chemical Reactions cannot be used for? A. building and balancing chemical equations B. gathering information about elements C. viewing any chemical reaction in a laboratory D. viewing some chemical reactions in a laboratory 2.

Amount (mol) of Mn atoms in 62.0 mg of Mn

The molar mass of water (H2O) is 18.02 g/mol. Yun needs 0.025 mol H2O for a laboratory experiment. She calculates that she needs 72.0 g H2O for the experiment. Yun's calculation was incorrect because she set up her unit conversion incorrectly.

I'm doing isotope homework and I need the find the number of protons, neutrons, and electrons first one is chromium-58 and chromium-63

Trisha and her lab partner were conducting a variety of experiments to produce gases: hydrogen, oxygen, and carbon dioxide. In one experiment, they added a piece of magnesium ribbon to 10 milliliters of hydrochloric acid.

what mass of magnesium is required to react with excess nitrogen to produce 0.500 mol magnesium nitrade

Silver chromate is sparingly soluble in aqueous solutions. the ksp of ag2cro4 is 1.12 * 10-12 m3. what is the solubility (in mol/l) of silver chromate