- Nucleus is a part of an atom
- If something is part of another thing, then another thing consist of that something
- Hence, an atom consists of a nucleus

- An atom consists of a nucleus
- Electrons surround / orbit the nucleus of an atom
- So, an atom consists of a nucleus surrounded by electrons

Hence, an atom consists of a nucleus surrounded by electrons
Q: An atom consists of a nucleus surrounded by
Context:
- Nucleus is a part of an atom 
- Electrons surround / orbit the nucleus of an atom 
- If something is part of another thing, then another thing consist of that something