That's what scientists and other technical people call the object's "<em>volume</em>".
Answer:
a) 2232nm
b) 2511nm
Explanation:
a) To find the path difference Δl you use the following formula:

m: order of a bright fringe
λ: wavelength of light = 558nm
for m=4:

b) The path difference for the case of destructive interference you have:

m: order of a dark fringe
for m=4:

A scalar or scalar quantity in physics is a physical quantity that can be described by a single element of a number field such as a real number, often accompanied by units of measurement. A scalar is usually said to be a physical quantity that only has magnitude and no other characteristics.