You need 1.25 kg of gas. Candles don't consist solely of oxygen, the ones the Russians use utilize lithium perchlorate (LiClO4). When they finish burning, you are left with a lithium chloride ash (LiCl), which will be 40% mass of what you started with.
It works out to be more efficient, at least in terms of mass, to send up large tanks of compressed gas instead.
It works out to be more efficient, at least in terms of mass, to send up large tanks of compressed gas instead.