The force of gravity on the object is the same all the time ... doesn't matter
whether it's in the air, in a box, or in corn syrup.
So when it's in corn syrup, the difference must be the buoyant force.
0.83N - 0.71N = 0.12 Newton
I'm sorry, but I just have to say how disappointed I am that you couldn't
get through this one on your own.