An aluminium sphere is dipped into water at 10⁰C.If the temperature is increased ,the force of buoyancy
1)will increase
2)will decrease
3)will remain constant
4)may increase or decrease depending on the radius of the sphere.

well as temperature increase there will be slight change in volume of aluminium but yes water density will decrease in considerable amount .. as water density decrease so weight of the volume displaced by the aluminium sphere will decrease so buoyancy will decrease .