The purpose of the Chi-Square Goodness of Fit statistical test

What is the purpose of the Chi-Square Goodness of Fit statistical test, give an example?
What is the purpose of the Chi-Square Independence Test statistical test, give an example?
Why do you need to know the standard error of the mean when you are testing hypotheses for differences of means?
What are major differences between a z-Test or a t-Test for the mean of a sample compared to the mean of the population?
How a z-score can establish the relative position of an individual with respect to the population in regard to a variable such as height or IQ? What are the usual minimum and maximum z-scores?