Do the following statements (1)and (2) have exactly the same meaning? Provide a counter example to each statement, or explain why a counter example is not possible. For the following conditional claims (a), (b) and (c) identify the sufficient condition and the necessary condition, say whether a counter example is possible, and give a counterexample where possible.
(1) If you learned it earlier then you must know the answer now.
(2) If you know the answer now then you must have learned it earlier.
(a) Every human has 23 pairs of chromosomes.
(b) Only planets have an atmosphere.
(c) All living organisms respire.