Answer:
elliptical orbit
Explanation:
There are three laws of planetary motion, which are called Kepler's law of planetary motion.
First Law : It states that all the planets revolve around the sun in an elliptical path and the sun is at one focus of that elliptical path.
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The correct matches are as follows:
<span>1. first nuclear reactor
</span>Fermi - an italian physicist who made the first nuclear reactor<span>
2. </span>1/0 η<span>
</span>atomic mass <span>
3. decaying nuclei
</span>fission<span> - nuclear reaction from a heavy elements to lighter elements
4. number of neutrons and protons
</span>neutron <span>
5. builds heavier elements
</span>fusion - nuclear reaction from two or more elements to a heavier element<span>
6. discovered radioactivity
</span>Curie<span>
7. unit of radiation
</span> Becquerel
Melting freezing and boiling are molecular changes