What evidence supports the conclusion that a chemical reaction has occurred?

( video about synthesis reaction)

Every compound can be represented by a chemical formula. a chemical formula is the set of symbols showing the elements that make up a compound and their proportions. water’s chemical formula is h 2 2 o. that means a molecule of water contains two atoms of hydrogen and one atom of oxygen chemically bonded. a molecule is a group of two or more atoms bonded together. molecules can range in size from two to thousands of atoms. a molecule of a compound is the smallest unit of that compound. every molecule of water has all the physical and chemical properties of water. that’s because every molecule of water is made of the same elements in the same proportions: two hydrogen atoms and one oxygen! which of the following is a true statement? a every molecule of the same compound will have different properties. b every molecule of a compound has the same proportion of elements. c molecules can be physically separated into smaller units of a compound. d molecules cannot be represented by chemical formulae.

All living organisms are composed of a. only one cell. b. at least 100 cells. c. at least three cells. d. one or more cells.

What is an endocrine function? (apex) a.esophageal glands release mucus into the esophagus b.salivary glands release saliva into mouth c.swear glands release sweat to the skin d.the pineal gland releases melatonin into the bloodstream