If a gas expands from 4L to 9L, what is the starting pressure if the final pressure was 80kpa? Round to the first whole number.

2nd bullet point: negative
3rd bullet point: some alpha particles bounced back because positive particles in the nucleus repelled them.
5th bullet point: positive
6th bullet point: neutral
7th bullet point: negative
8th bullet point: neutrons and protons
9th bullet point: electrons
10th bullet point: The atomic number symbolizes how many protons are in the atom.
11th bullet point: The atomic number.
12th bullet point: You subtract the number of protons from the mass number.
13th bullet point: They are isotopes of the element oxygen.
14th bullet point: 74
15th bullet point: P=50 N=72 E=50
16th bullet point: 68
17th bullet point: isotopes
18th bullet point: atomic= 18 mass= 38
19th bullet point: the number of protons determines the number of electrons, which determines the chemicals' properties and mass.
20th bullet point: its atomic mass, the number of protons in a certain atom, and its electronegativity.

CHART
carbon=6
sodium=11
silicon=14
nitrogen=7
oxygen=8
calcium=20

Last bullet point: The atomic mass is the weighted mass, while the mass number is simply the number of protons and neutrons added together. Both use the unit AMU, or atomic mass unit.

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