Assertion : The clouds in sky generally appear to be whitish. Reason : Diffraction due to clouds is efficient in equal measure at all wavelengths.

Step-by-step solution

The clouds consists of dust particles and water droplets. Their size is very large as compared to the wavelength of the incident light from the sun. So there is very little scattering of light. Hence the light which we receive through the clouds has all the colours of light. As a result of this, we receive almost white light. Therefore, the cloud are generally white.