12 constellation self-made context bookmark tutorial

A, veins bookmarks produced new substances in the process of preparation, which belongs to chemical changes.

B, no new substances are produced in the process of water purification, which belongs to physical changes.

C, self-made soda ash process produces new substances such as carbon dioxide, which belongs to chemical changes.

L, egg shell into vinegar, produce new substances such as carbon dioxide, belongs to the chemical change.

Therefore, choose: B.