Surgical implements
Arpeggio
I believe you are describing hatching.
On an electrical schematic it designates that the wires are all connected together. It is called a connection point.
A well placed observer can compromise the entire operation is security. The site must be secure from attack and from observation.
Two or more kinds of matter placed together but which can be easily separated is called a mixture. In a solution, the stuff that is dissolved (the solute) "disappears" into the liquid (solvent) and separating the two isn't as easy as separating a mixture.
security
Usually placed together but, if there are values, within the overall range, for which no observations are possible, they could be spaced out.
Security
security
No.
All of the continents placed together
it was then placed in the pyramids built for them wich were called tombs