Question

What is the name of (NH4)2 G2O7

Answer 1

I think you are referring to $( NH_{4} )_{2}$  $Cr_{2} O_{7}$ and not G207 as given in the question. There is no element with the symbol 'G'. 

I am not aware in what context you are referring to them, but I am considering you need the name of the compound. The name of this compound is 'Ammonium Dichromate'.

The ions present are:
$NH_{4}$+ = Ammonium Ion
$Cr_{2} O_{7} ^{2-}$ = Dichromate ion

Thus, the name is Ammonium Dichromate and the formula is $( NH_{4} )_{2} Cr_{2} O_{7}$  after balancing the charge.

Based on my research, I found this question to be from a vacation assignment worksheet of a particular school, it must be a typographic error.

Therefore, the answer must be Ammonium Dichromate if the formula is  $( NH_{4} )_{2}$  $Cr_{2} O_{7}$. Similarly, you can name it for any other compound which was actually supposed to be there.

Answer 2

Answer:

it's ammonium dichromate