The elements of sets A , B and C are all colours as follows:
A = { Red , Orange , Yellow , Brown } ,
B = { Blue , Yellow , Green , Brown } ,
C = { Black , Brown , White , Grey }
Then, A U B U C is
In the spectrum of white light by a prism, the colour at the extreme end opposite to the base of prism is :
(a) violet (b) yellow
(c) red (d) blue.
The colour of light absorbed by an aqueous solution of CuSO4 is