11.Two solids A and B float in water. It is observed that A floats with half of its volume immersed and B floats with 2 / 3 of its volume immersed. The ratio of densities of A and B is

12.A piece of material weighing 50 g is coated with 6.3 g of wax of relative density 0.9. If the coated piece weighs 16.3 g in water, the density of the material is

13.A piece of brass (Cu and Zn) weighs 12.9 g in water, it weighs 11.3 g. The relative densities of Cu and Zn are 8.9 and 7.1 respectively. The mass of copper in the alloy is

14.When a large bubble rises from the bottom of a lake to the surface, its radius doubles. The atmospheric pressure is equal to that of a column of water of height H. The depth of the lake is

15.In a hydraulic lift at a service station, the radii of the large and small pistons are in the ratio of 20 : 1. What weight placed on the small piston will be sufficient to lift a car of mass 1200 kg ?