Answer: Leeuwenhoek biggest contribution is to the first tenet of the cell theory.
Explanation: the first tenet of cell theory states that every living being is made of cells and even an organism can be made of just one cell able to reproduce by itself.
Leeuwenhoek observations stablish the existence of microscopic structures alive some with movement. This helped other scientists to determinate this structures were cells that can make vital processes such as feeding, breathing or reproducing which are determinant in biological definition of life.
Electromagnets can easily be turned on and off.
Explanation:
An electromagnet produces magnetic field which is done by the electric current. These electromagnets contain a wire would like a coil. The current passes through the wire and the magnetic field is concentrated in the center which is the "center of the coil".
When the current is "turned off" the magnetic field "disappears". This shows that we have can have a control over the passage of current or the magnetic field. Thus, the "main advantage" of the electromagnet is that it can be easily turned on and off whenever necessary.
True.
Tertiary sources compile and summarize secondary sources. Examples: reference publications such as encyclopedias, bibliographies, or handbooks
C- argon
This is because, an electrolyte is a solution that conducts electricity due to the presence of ions, and since argon is an atom and not an ion, it cannot conduct. Thus, it is a non-electrolyte