What is the effect on Fresnel's biprism experiment when white light is used?

The colours observed in thin soap bubbles are due to

In a biprism experiment,by using light of wavelength $5000 \ \mathring{A}$,$5 \,mm$ wide fringes are obtained on a screen $1.0 \,m$ away from the coherent sources. The separation between the two coherent sources is.....$mm$.

When petrol leaking from a vehicle falls on a rain-wet road,colours are observed. This is due to the.......... of light.

In a Fresnel biprism experiment,the eyepiece is placed at a distance of $120 \, cm$ from the source. The distance between the two virtual images is found to be $0.075 \, cm$. If the eyepiece is moved by $1.92 \, cm$ to cross $20$ fringes in the field of view,what is the wavelength of light in $\mathop A\limits^o$?

Calculate the minimum thickness of a soap film $(n=1.33)$ that results in constructive interference in reflected light, if the film is illuminated with light whose wavelength in free space is $532 \,nm$. (in $\,nm$)