Francium
Lithium is NOT the most active alkali metal. Francium is the most active but is available in such trace quantities and radioactive that for practical purposes it is Cesium that is considered most active.
chlorine
The most active metal in the calcium family is francium. It is the least stable alkali metal and can react violently with water, making it extremely rare and highly radioactive.
Largest.
Hydrogen...
The next is caesium.
carbon
No, a less active metal cannot replace a more active metal in a chemical reaction. In a single displacement reaction, a more active metal will displace a less active metal from its salt solution, but the reverse is not possible.
Potassium is the most active metal. It is highly reactive and can easily react with water to produce hydrogen gas and caustic potassium hydroxide.
Most metal musicians like, say Metallica use an active pickup. eg.( the EMG 81/85 )
The most active metal is francium (Fr). It is located farthest to the left and at the bottom. The most active nonmetal is fluorine (F). It is located at the top of Group 17 (the halogens).
Fluorine is the most active non-metal due to its high electronegativity, which allows it to readily gain an electron to achieve a stable electron configuration. Francium is the most active metal because it has the lowest ionization energy among all the elements, making it highly reactive and prone to losing an electron to form a positive ion.