Objects that weigh about 1 kilogram

A pineapple, a liter of water, a dictionary or a large book, a globe. 

A large book and a pineapple, dictionary, liter of water,a globe

1. Yes. to calculate the volume of a sphere you do , with a radius of 4, you get ≈268.08. then you have to calculate the volume of the cube, which is length x width x height, so you get ≈421.88.  421>268, so JD is correct

2. you need to find out how much weight a balloon with a diameter of one foot can hold, so you divide 8 by 8 to get one, and 17 by eight to get 2.125. You multiply that by 136 to get 289. The balloon would have to be 289 diameters to hold a 136 pound person.

Hope this helps :)