I think that the answer is A because if you think about water for an example. When water turns into ice, it's still technically water, just the molecules are frozen. The water is physically changed. It could also see why you think it is B but I don't think so completely. It doesn't really make sense to me. So I'd choose A. It's definitely not C or D.
<span>The key difference between Mendeleev and modern periodic table is that Mendeleev’s periodic table was based on the increasing atomic masses while the modern periodic table is based on the increasing atomic numbers. Let us see here what is Mendeleev periodic table and what is modern periodic table, and then compare both to understand the difference between both periodic tables. Mendeleev is the pioneer of the modern periodic table, though a numerous number of changes had been made to the old version of the periodic table. Both of these attempts are equally important to the scientific community; because without an invention of the periodic relationship in elements, the modern developments in Science would not reach a development era as today. Before the invention of Mendeleev’s classification, there were several attempts made by several chemists, but their periodic laws were inadequate to apply for all the elements. The modern periodic table is so advantageous for the development in the Science.</span>
It is used as a before and after or step by step proces
Answer:-
Neon is a noble gas. Neon with an electronic configuration of 2,8 has 8 electrons in it's outermost shell or valence shell.
According to the Octet theory if an element has eight electrons in it's valence shell then it is stable and does not undergo reaction. Thus Neon does not need to react and can exist freely in nature.
Sodium with an electronic configuration of 2,8,1 has 1 electron in it's valence shell. As per octet rule, it is not stable and it must lose that 1 electron to become stable.
In order to lose that 1 electron sodium must react with other substances. Hence sodium cannot exist freely in nature.