Which of the following will not break down due to a chemical change?
1.h2o
2.ne
3.n2o
4.hf

2. Ne  

Explanation:

Neon is an element. You cannot break down an element by chemical means.

1, 3, and 4 are wrong. They are all compounds, and compounds can be broken down by chemical means.

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.