For the oxidation-reduction reaction equation given here,

2Rb+Br2 --> 2RbBr

Indicate how many electrons are transferred in the formation of one formula unit of product.

To determine the number of electrons transferred in the formation of one formula unit of product in an oxidation-reduction (redox) reaction, you need to identify the change in oxidation states of the elements involved.

In the given reaction:

2Rb + Br2 → 2RbBr

We can see that Rb goes from an oxidation state of 0 to +1 in RbBr, while Br2 goes from an oxidation state of 0 to -1 in RbBr.

Since there is a transfer of one electron from the Rb to Br2, we can conclude that one formula unit of product (RbBr) is formed by the transfer of one electron.

Therefore, one electron is transferred in the formation of one formula unit of RbBr.