1 Which of the following statements is incorrect?
А
The addition of water to quicklime is an
example of a physical change.
B
A chemical change is irreversible and a new
substance is formed.
С
A physical change can easily be reversed
and no new substances are formed.
D Separating a mixture by distillation is an
example of a physical change.​

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.