Question

Is amplitude a scalar or vector physical quantity?(sound wave).Also mention the reason for what type of quantity it is.

Answer 1

A scalar quantity is one that only requires one number to describe it, or to put it another way its only attribute is its size.

A vector quantity is one that requires a one-dimensional list of numbers to describe it, or to put it another way its only attributes are its size and its direction.

So amplitude is strictly speaking a scalar. Whenever you need to describe a (polarised) vector oscillation such as an EM wave, you would use a separate polarisation vector as well as the amplitude. But that’s only really a convention, it’s not like a law of physics or something