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Vanyuwa [196]
3 years ago
9

Will give brainliest

Chemistry
1 answer:
mote1985 [20]3 years ago
7 0

Answer:

1)Around 450 B.C., the Greek philosopher Democritus introduced the idea of the atom.

2)All matter is made of atoms, Atoms are indivisible and indestructible.Compounds are formed by a combination of two or more different kinds of atoms, A chemical reaction is a rearrangement of atoms.

3)B

Explanation:

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4 years ago
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Answer:

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Looking at the periodic table 4th row for the alkaline-earth metal, we can find Calcium which has an atomic number of 20 (or protons number, or z). The mass number is given by the sum of protons and neutrons. If the number of protons in this case is 20 and the number of neutrons is also 20, the mass number A = 40.

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Answer:

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Science 6th grade please help me :)
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