Help needed from MATH GURU only

My friend I would really appreciate it if you could answer these 4 questions for me in the next 6 to 8 hours if not, no problem.  Thanks

1    Compare and contrast internal and external validity. Describe and
give examples of research questions for which external validity is a primary
concern. Describe and give examples of research questions in which internal
validity is a primary concern. Discuss strategies researchers use in order
to make strong claims about the applicability of their findings to a target
population.
2    Compare and contrast random selection and random assignment. Be sure
to include a discussion of when you would want to do one or the other and
the possible consequences of failing to do random selection or random
assignment in particular situations.
3    Explain the relationship between sample size and the likelihood of a
statistically significant difference between measured values of two groups.
In other words, explain why, all else being equal, as sample size increases
the likelihood of finding a statistically significant relationship
increases.
4    Compare and contrast probability and non-probability sampling. What
are the advantages and disadvantages of each?