What initial observation led to the Alvarez asteroid-impact theory? a large undersea crater off the coast of the Yucatan Peninsula in Mexico high iridium levels in a 66-million-year-old clay layer in Denmark and Italy large concentrations of shock-fractured quartz in rock layers found in Europe dinosaur remains found near a large crater formed by an asteroid impact

How does a scientist the government? a. the scientist tells people in society what to do. b. the scientist determines the policies that the government spends money on. c. the scientist provides unbiased information to the government. d. the scientist makes laws based on his or her research results.

Which of the following elements would you expect to have the lowest ionization energy value? fluorine, lithium, neon, nitrogen

For each of the following compounds, write the formula then predict whether it would be a strong, weak, or non-electrolyte when placed in di water. for the ionic compounds only, put (s) or (aq) after the forrmula formula strong, weak or non electrolyte? a calcium hydroxide b. silver carbonate c. lead(ii) sulfate d. phosphorus trifluoride e. sodium phosphide f barium sulfate g. strontium acetate h. zinc nitrate