What type of reaction occurs when one element or ion within a compound is exchanged with another element or ion? combustion
decomposition
single-displacement
double-displacement

When an element replaces another in aone element or ion within a compound is exchanged with another element or ion , the reaction is called 

1. a)c-14 has two more protons

2. d)they have different numbers of protons, neutrons, and valence electrons; they are all gases at room temperature.

3. c) iron and nickel.