Only one if the balloon has enough heilum. You may want to restate the question more succinctly.
ans 2
At standard conditions:
22.4 Liters of air weighs approximately 29 grams
22.4 Liters of helium weighs 4 grams
29 grams - 4 grams = 25 grams
That means that each 22.4 Liters of helium provides a buoyant force of 25 grams. 22.4 Liters / 25 grams = 0.896 Liters/gram
There are 454 grams in 1 pound
454 grams/pound x 0.896 Liters/gram = 407 Liters/pound
If you hook 407 1-Liter helium balloons to the 1-pound object, it would neither sink nor float. To lift the weight, you'd need "more than 407 1-Liter balloons".
This presumes that the weight of the balloons is figured into the 1 pound. If not, you'll need to find the weight of the 407+ empty balloons.
ans 3
Since you get the same result with one balloon with a capacity of 407 liters + 1 liter, I say again that the number of balloons is irrelevent unless you state their capacity as part of the question.