Answer
Silver dichromate.
Work Step by Step
Silver ion $(Ag^{+})$ has a +1 charge and dichromate ion ( $Cr_{2}O_{7}^{-2})$ has a -2 charge. In order to balance charges, 2 atoms of silver ions should be present. Thus, the chemical formula will be $Ag_{2}Cr_{2}O_{7}$ and the name of the ionic compound will be Silver dichromate.
