You're correct It's D :))))))))<span />
1. <span>The region in which an electron is most likely to be found is called an orbital.
2. </span>An atom in which an electron has moved to a higher energy level is in an excited state.
3. When Mendeleev organized elements in his periodic table in order of increasing mass, elements with similar properties were in the same column.
4. Mendeleev’s periodic table was useful because it enabled scientists to predict properties of unknown elements.
The following substance must be an A. Compound.