What are 20 physical changes ?

Crushing a can.

Melting an ice cube.

Boiling water.

Mixing sand and water.

Breaking a glass.

Dissolving sugar and water.

Shredding paper.

Chopping wood.

Explanation:

Crushing a can

Melting an ice cube

Boiling water

Mixing sand and water

Breaking a glass

Dissolving sugar and water

Shredding paper

Chopping wood

Mixing red and green marbles

Sublimation of dry ice

Crumpling a paper bag

Melting solid sulfur into liquid sulfur. This is an interesting example since the state change does cause a color change, even though the chemical composition is the same before and after the change. Several nonmetals, such as oxygen and radon, change color as they change phase.

Chopping an apple

Mixing salt and sand

Filling a candy bowl with different candies

Vaporizing liquid nitrogen

Mixing flour, salt, and sugar

Mixing water and oil

Explanation:

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.