An aluminium sphere is dipped into water at 100C.If the temperature is increased ,the force of buoyancy1)will increase2)will decrease3)will remain constant4)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 .