It is a physical change because you can not put it back like it was
Explanation:
Physical changes only change the appearance of a substance, not its chemical composition.
Chemical changes cause a substance to change into an entirely substance with a new chemical formula.
Chemical changes are also known as chemical reactions. The “ingredients” of a reaction are called reactants, and the end results are called products
The answer is B. is the energy source of stars.
Fission is the type of nuclear energy simulated on Earth, as it is the one used to generate electricity. Fusion, on the other hand, is much more complicated to achieve because it requires extremely hot temperatures compared to fission. Fusion involves the combination of two hydrogen atoms to make helium, which releases a lot of energy. Stars such as the sun, exhibit fusion with its very hot temperature and abundant source of hydrogen.
Explanation:
Since, the atomic number of nitrogen is 7 and its electronic distribution is 2, 5. So, in order to attain stability it needs to gain 3 electrons.
Hence, when it chemically combines another nitrogen atom then as both the atoms are non-metals. So, sharing of electrons will take place.
Also, there is no difference in electronegativity of two nitrogen atoms. Hence, compound formed 
is non-polar covalent in nature.
