Asubstance which contains various elements or compounds without bonding or in fixed proportions is a(n)

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.

In chile, the deepest earthquake occurred at 61.7°w longitude at a depth of 540 km. if the rocks at the focus began subducting 10 million years ago and are now 1000 km from their original position, what is the average rate of subduction in cm/yr?

Sodium azide is a substance that can be used to inflate airbags.an electrical impulse causes the sodium azide to decompose,producing elemental sodium and nirtogen gas.write the balanced chemical equation for this reaction. plzzz