Nascent oxygen has much higher reactivity than the oxygen bubbled through the reaction mixture. It doesn't stay nascent for long (you are right about it being converted quick to just O2), which is why it has to be generated in situ
Answer : The mass of
required is 18.238 grams.
Explanation : Given,
Mass of
= 83.10 g
Molar mass of
= 146 g/mole
Molar mass of
= 256.52 g/mole
The balanced chemical reaction is,

First we have to determine the moles of
.

Now we have to determine the moles of
.
From the balanced chemical reaction we conclude that,
As, 8 moles of
produced from 1 mole of 
So, 0.569 moles of
produced from
mole of 
Now we have to determine the mass of
.


Therefore, the mass of
required is 18.238 grams.
Refer to the attachment for answer.
SOME EXTRA INFORMATION:
Bromo is used for Bromine (Br)
Chloro is used for Chlorine(Cl)
'ene' represents double bond between carbon atoms.
'ol' is used for alcohol
HOPE IT IS USEFUL