A mineral always contains certain elements in definite proportions
In the logical sense, sentences must be either true or false and not both. "This sentence is false" cannot be true because that would mean that it is false, and it cannot be both. It also cannot be false because that would mean that it is true, and it cannot be both. Therefore, if it is true or false, then it is both true and false. Therefore it is either neither true nor false or both true and false; therefore, in the logical sense, it is not a sentence. However, it says it is a sentence; therefore, it is lying; therefore, it is false.
True
False.
false
false
false
Because it is neither true or false until the variable is replaced with a specific value making the sentence true or false.
true
My teacher told me to write true or false for the statement.
false
By knowing your material. If you have kept up with your work, it will be obvious whether a sentence is true or false.
The two sentences create a logical paradox. The first sentence is false. But that would make it true. But that would make it false. Similar is the Liar's Paradox: A man who always lies says "I am lying." In this case the premise must be false, or the statement cannot be valid.