If the intensity of the incident radio wave is $3watt{m}^{-2}$ is reflected by the surface, the pressure exerted on the surface is  $\_\_\_\_\_\times {10}^{-8}N/m^2$

Pressure exerted by reflected wave on the surface is  $P=\frac{2I}{C}$
Intensity of incident radio wave is $I=3watt{m}^{-2}$ and Velocity of light  $C=3\times {10}^{8}m{s}^{-1}$
Pressure  $P=\frac{2\times 3}{3\times {10}^8}=2\times {10}^{-8}N/m^2$