Answer: chemical change
Step-by-step explanation:
A physical change is defined as a change in which there is alteration in shape, size etc. No new substance gets formed in these reactions. Example: Evaporation of water
A chemical change is defined as a change in which a change in chemical composition takes place. A new substance is formed in these reactions. Example: Combustion
As in the given reaction, fat comes in contact with sodium hydroxide to produce soap and glycerin, it will be a chemical change as new substances are being formed.
triglyceride + sodium hydroxide glycerol +3 soap molecules