The chemical composition of soil varies with depth. an article in communications in soil science and plant analysis describes chemical analyses of soil taken from a farm in western australia. fifty specimens were each taken at depths 50 and 250 cm. at a depth of 50 cm, the average no3 concentration (in mg/l) was 88.5 with a standard deviation of 49.4. at a depth of 250 cm, the average concentration was 110.6 with a standard deviation of 51.5. find a 95% confidence interval for the difference in no3 concentrations at the two depths.

Many reactions take place in aqueous solution. when potential reactants are mixed, a reaction will occur if there is some driving force that favors the formation of products. it is often convenient to categorize reactions in terms of these driving forces: precipitate formation, in which an insoluble solid is formed, weak electrolyte formation, as in a neutralization reaction involving water, or transfer of electrons, as in a redox reaction. these reactions can be represented by full molecular equations, which contain all species in the reaction mixture, or by net ionic equations, which show only the species that actually undergo a change. the latter does not contain the spectator ions, which do not undergo a net change or do not take part in the reaction. part a when the following two solutions are mixed: k2co3(aq)+fe(no3)3(aq) the mixture contains the ions listed below. sort these species into spectator ions and ions that react. drag the appropriate items to their respective bins. view available hint(s) spectator ions ions that react part b what is the correct net ionic equation, including all coefficients, charges, and phases, for the following set of reactants? assume that the contribution of protons from h2so4 is near 100 %.ba(oh)2(aq)+h2so4(aq)→ express your answer as a chemical equation. view available hint(s) nothing provide feedback

George is a dalmatian puppy. describe what happens to light that allows you to see george’s black and white coat.

Why does earth rotate? because earth is formed from cold gases collapsing due to gravity because the matter in the nebula that formed earth was spinning because earth forms more than 99% of the mass of the solar system because the hydrogen atoms inside the nebula fused to form helium