If you mean his predictions about the Periodic Table then yes his predictions were correct.
Knowledge, experience, and our ability to extrapolate past trends into the future help to make predictions about the future, but do not guarantee those predictions will come to pass.
qualitative
Albert Einstein first proposed the idea that gravity bends the fabric of space in 1911. He and David Hilbert fully developed it in a mathematical framework in late 1915. Arthur Eddington reported in 1919 that Einstein's predictions were correct, but there was controversy over whether his statements were valid. Measurements from the 1922 eclipse in Australia left no doubt but that Einstein was correct.
meteorology
A meteorologist.
no
Mendeleev predictions were correct.
yes
Theories are explanations for natural phenomena based on facts which produce correct predictions. So, you need a LOT of foundational evidence and correct, testable predictions.
They seem to be, yes.
50% right, 50% wrong
Great sources for NFL predictions would include your favorite NFL news sites. Just make sure you choose the correct category such as Fantasy or real football.
UFC 161 Predictions
So you do not lose interest and keep reading to find out if what you foreshadowed is correct.
Probably not because there have been other theories from the nostrdamus about the apocalypse like in 2008, 2002, and 2007. So probably not.
Predictions
No theories are correct. That is why they are called theories. These are the best that can be done with present knowledge, they explain and make prediction that could otherwise not be made. If those explanations are useful and the predictions turn out to be correct it strengthens the theory. It does not prove it. When a theory is proven to be true it is then called a law.