Question

to show breakdown of food by using the model of chalk piece kept in vinegar

Answer 1

The food we eat goes through a series of modification In the digestive tract. One such compartment is stomach. Stomach has a acidic environment and so the pH is very low. Here the food that enters through esophagus is converted to acidic chyme and proteins are digested, i.e breakdown into amino acids.
To show this a model of chalk kept in Vinegar comes in picture.
Chalk as we know has calcium init will be broken-down by the acidity of Vinegar or acetic acid. Thus depicting how digestion occurs.
Thats how you can corelate the two!