1. Ca → Element
2. Proton → positive
3. H2O → compound
4. Fission → nuclear decay
5. Fusion → Nuclear synthesis
6. η → Neutron
7. e → electron
8. Atomic number → no of protons in nucleus.
Explanation
1. Ca (Calcium):
Calcium is an element with the atomic number of 20. It is an alkaline earth metal. The 99% of calcium is found in our bodies, in bones, teeth.
2. Proton:
Proton is a subatomic particle and it holds the positive charge. Proton is present in the nucleus of the atom.
3. H2O (water):
Water is a chemical compound and it's chemical formula is H2O. It's called compound as it contains 2 hydrogen and 1 oxygen atoms bonded together through the covalent bond.
4. Fission:
Fission is a process in which large massive unstable nucleus splits into the smaller, less heavier and stable nuclei. The energy is re;eased in the form of radiations during this process. It's called as the radioactive decay.
5. Fusion:
Fusion is opposite of the fission reaction. As in this case the two nuclei combines to form a single large nucleus. That's why it is a nuclear synthesis process.
6. η neutron:
Neutron is a subatomic particle and it is a neutral particle which is located inside the nucleus. n is a symbol used for the neutron.
7. e Electron:
The symbol for electron is e. It's a subatomic particle with negative charge. It is found in the orbits around the nucleus.
8. Atomic Number:
Atomic number is defined as the number of protons in the nucleus of an atom. IT is represented by Z.
If you’re talking about atoms, I hope this helps
Atoms consist of three basic particles: protons, electrons, and neutrons. The nucleus (center) of the atom contains the protons (positively charged) and the neutrons (no charge). The outermost regions of the atom are called electron shells and contain the electrons (negatively charged)
Answer:
Explanation:
Given
mass of boy 
mass of girl 
speed of girl after push 
Suppose speed of boy after push is 
initially momentum of system is zero so final momentum is also zero because momentum is conserved
i.e. velocity of boy is 2.82 m/s towards west
