The solubility of CaF2 (Ksp=5.3×10−9) in 0.1 M solution of NaF would be : (Assume no reaction of cation/anion) .
For a wave, displacement amplitude is 10−8 m, density of air is 1.3 Kg/m3, velocity in air is 340 m/s and frequency is 2000 Hz. The intensity of the wave will be given by