The percentage composition of oxygen is 80%.what does it mean?

or there is 80% oxygen

Percent Composition Definition. Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. Percent composition is the percentage by mass of each element in a compound . Example: The percent composition of water is 20% hydrogen and 80% oxygen.

Explanation:

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

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