Question

if a prisms angle is 60 degree 5 min then its dispersive powr

Answer 1

I think some data is missing from the question... Angles of minimum deviation are not given for different colors.  Or, we need to be given the refractive indices of the prism for colors  Red, violet and yellow.

let the angles of minimum Deviation for violet , red and yellow = Dv , Dr , Dy
Refractive indices of a prism wrt color violet red and yellow = μv, μr, μy

   prism angle = A
       μ = Sin ((A+D)/2) / Sin(A/2)

       Dispersive power of the prism = ω = (μv - μr) / [ μy -1 ]
             or,              ω =   (μv - μr) / (μ - 1)        where μ = (μv + μr)/2

  So we can see that some additional data is to be given D or μ.