Question

3. All the mass of an atom is concentrated in it
4. A subatomic particle that is electrically neutral
5. Arrangement of electrons in different shells of an atom
6. The outermost shell of an atom​

Answer 1

Answer:

3. Nucleus

4.electron

5.2,8,8and so on

6.valence shell

Explanation:

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Answer 2

Answer:

3.nucleus of an atom

4.neutron

5.2,8,8,so on

6.valence shell

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Explanation: