Question

Which of the following is the most reactive metal?
A. Copper
B. Gold
C. Silver
D. Francium

Answer 1

Hint: It's the most stable isotope, it is extremely radioactive , originally called actinium K after the natural decay chain it appears in. It is rare due to the distance of its electrons from the nucleus and its atomic number.

Complete answer:
Francium is an alkali metal in group 1/IA. All alkali metals have one valence electron. As you go down the group, the number of electron energy levels increases – lithium has two, sodium has three, etc, as indicated by the period number. The result is that the outermost electron gets further from the nucleus. The attraction from the positive nucleus to the negative electron is less. This makes it easier to remove the electron and makes the atom more reactive. Francium is hypothesized to be the most reactive metal, but so little of it exists or can be synthesized, and the longest half-life of its most abundant isotope is 22 minutes, so that its reactivity cannot be determined experimentally.

Let's learn about reactivity series,
The reactivity series is a series of metals, in order of reactivity from highest to lowest. It is used to determine the products of single displacement reactions.The reactivity series lists metal compounds, are those at the top and bottom are most keen to react with other elements to form compounds. Less reactive metals will displace other metals from their compounds.

Hence, Francium is the most reactive metal, which is option D.

Note: Francium is a laboratory produced element and only minute quantities have been made, so it is only used for experimental purposes and Cesium is used for all practical purposes. If Francium reacts to water, it would cause a huge explosion and that would be fatal, it is that reactive.