Economic Systems: The economy of Ancient Greece was very large because of the imported goods but ancient Greece had poor soil. The currency they used is a medium level of trading and using a coin called a Athenian coin.
An argument is invalid if and only if all the premises is true and the conclusion is false.
We can test the invalidity of the argument by assuming all the premises are true and seeing whether it is possible for the conclusion to be false. If the conclusion is possible to be false, then, the argument is invalid.
A valid argument, on the other hand, is valid if and only if it is necessary that:
1) if all of the premises are true, then the conclusion is true
2) if all of the premises are true, then the conclusion must be true
3) it is impossible that all the premises are true and the conclusion is false.
The correct answers to the following questions are :
(1) Vertical columns in the periodic table indicate D.groups and families
(2) families of elements includes A.metals and noble gases
(3) <span>the atomic mass of many elements not a whole number because </span>B.An element may have isotopes with different numbers of neutrons.
