Is the Concept of validity and reliability applicable in examination?

It is important to understand the differences between reliability and validity. Validity will tell you how good a test is for a particular situation; reliability will tell you how trustworthy a score on that test will be. You cannot draw valid conclusions from a test score unless you are sure that the test is reliable.

melody. a series of single tones which add up to a recognizable whole is called a what kind of layers of sound are heard melody or harmony. how many layers