D.)Most of the mass of an atom is located in the nucleus.
Explanation:
Rutherford conducted his famous gold foil experiment which refined our understanding of the structure of an atom. Through the experiment he observed that when positively charged alpha particles were bombarded against a thin gold foil, majority of them passed through the foil undisturbed whereas a small percentage retraced their path.
There were two main conclusions:
-Since most alpha particles simply passed through undeviated this suggested that majority of the space inside the atom is empty
- Also, since some of them completely bounced back this suggested that there is a positively charged core in which the mass of the nucleus is concentrated.
When the graduation line denotes the volume contained in the calibrated vessel, the ware is marked “TC”. When the graduation line indicates the volume delivered from the vessel, the ware is marked “TD”.
The evidence that a chemical reaction occurred is can be change in color , formation of a precipitate , Here in the case when 6 m HCl to the solution of sodium acetylsalicylate, the formation of precipitate that is of aspirin takes places that can be taken as a evidence that a reaction is occured. The reaction can be seen in the image attached.
