A1br3 and 3k and 3k and 3kbr and a1 are an example of what reaction

It is an example of single displacement reaction.

Explanation:

Single replacement reaction:

A single element replaces another element in a compound.

For example,

The given reaction is as follows.

In the above reaction, aluminium bromide is dissociated into the , these bromide ions are reacted with potassium atoms to form potassium bromide.

Here, only one element  displaces therefore, it is an single displacement reaction.

"the periodic table is arranged in order of atomic number."