Define changes in acceleration found on P-T and V-T graphs

PLZ RESPOND FAST ;-;

What is the answer for this. the correct answer only

Light from a sodium lamp passes through a diffraction grating that has 1000 slits per millimeter. the interference pattern is viewed on a screen 1.000 m behind the grating. the first (m = 1) two bright yellow fringes that are visible are 0.7288 m and 0.7300 m from the central maximum. what are the wavelengths of these two fringes?

If the chemical properties of a substance remain unchanged and appearance or shape of a substance changes it is called a ?