We can observe physical properties of elements and compounds without changing the substance.
Examples of physical properties: Density, color, boiling point, state of matter, appearance: dull or shiny, etc.
But we can also observe and measure chemical properties by reacting a substance with something else. For example, like mixing baking soda and vinegar together. The vinegar reacts with the baking soda and produces carbon dioxide: a new substance.
Some examples of chemical properties: Flammability, amount of heat that is released during combustion, toxicity (how much damage it causes to other organisms), radioactivity, and ability to oxidize (when you have metal that becomes rusty looking).
The electrons hold onto the nucleus because of the magnetism and the electricity. <span />
C - electric charges have electric fields. imagine a magnet - charge is distributed in space in the same way magnetic field is. if you can imagine how two magnets of the same sign (++/--) repel each other, you can apply that concept to electric charge/field.
Option D.
A voltaic cell need tha anode, the cathode and the electrolyt to work.
Volitmeter is just an equipment to measure the functioning of the voltaic cell.