A metallic sphere of mass 1 kg and volume 2 × 10-4 m3 is completely immersed in water. The buoyant force exerted by water on the sphere is : (Given : density of water = 1000 kg/m3, g = 10 m/s2)

According to Archimedes' principle, the buoyant force acting on an object submerged in a fluid is equal to the weight of the fluid displaced by that object. For a completely immersed object, the volume of the displaced fluid is equal to the volume of the object itself. The formula for calculating this buoyant force is $F_B = \rho \times V \times g$, where $\rho$ is the density of the fluid, $V$ is the volume of the displaced fluid, and $g$ is the acceleration due to gravity. Given the density of water as $1000\text{ kg/m}^3$, the volume of the sphere as $2 \times 10^{-4}\text{ m}^3$, and $g$ as $10\text{ m/s}^2$, the calculation is: $F_B = 1000 \times (2 \times 10^{-4}) \times 10$. This simplifies to $1000 \times 0.0002 \times 10$, which equals $2\text{ N}$. Thus, the buoyant force exerted by the water is $2\text{ N}$.