Fe + CuSO4 → FeSO4 + Cu
What type of reaction is shown above?

A single replacement reaction

There are two types of chemical reactions that may occur.

namely single-replacement reactions and double-replacement reactions.

A single replacement reaction is a chemical reaction in which one element replaces the other elements of a compound to produce new elements and compounds

Not all of these reactions can occur. We can use the activity series, which is a list of elements that can replace other elements below / to the right of them in a single replacement reaction.

This series is better known as the Volta series, where the metal element with a more negative electrode potential is on the left, while the element with a more positive electrode potential on the right.

The more left the position of a metal in the series, the more reactive metal (easy to release electrons, the stronger as the reduction agent)

The metal activity series is expressed in voltaic series  

Li-K-Ba-Ca-Na-Mg-Al-Mn- (H2O) -Zn-Cr-Fe-Cd-Co-Ni-Sn-Pb- (H) -Cu-Hg-Ag-Pt-Au  

Fe(more active element) takes the place of Cu(less reactive element) in the CuSO4 compound

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates