Question

The danger signals installed at the top of tall buildings are red in
colour. These can be easily seen from a distance because among all
other colours, the red light
(a) is scattered the most by smoke or fog
(b) is scattered the least by smoke or fog
(c) is absorbed the most by smoke or fog
(d) moves fastest in air

NCERT Class X
Science - Exemplar Problems

Chapter_The Human Eye and
the Colourful World

Answer 1

option b is correct because if the light will scatter less it will have a focussing effect.
 this is primarily because the wavelength of red colour is the largest.

Answer 2

the danger signals installed at the top of tall buildings are red in colour because among all other colours, red colour is scattered the least by smoke or fog. this is primarily because the wavelength of red colour is the largest.thus it can easily be seen from a distance.