Are you acidic?

I don't know if some of us has been asked this question already. I was quite surprise getting hold of an information about acidity as a serious problem. I did not know that it can cause cancer, hypertension, anemia, obesity, osteoporosis, tuberculosis and kidney stones. They say stress is a major cause of acidity. Is this the reason why stressed people often have ulcers? or high gastric juices? Ill effects of acidity includes a stressed out condition, depression, constipation, muscle and body pains, headaches, insomnia, weight loss or gain, lack of focus and concentration, forgetfulness, acne, eczema, dry skin, premature hair loss.

How do we find out if we are acidic? Is there such a thing as acidity level? I am dying to find out if there is such a thing. Can anyone enlighten me on this matter please? Thanks in advance!