In Young’s double slit experiment the phase difference between the waves reaching the central fringe and fourth bright fringe will be

Path difference between the waves reaching the central fringe and 3rd bright fringe is equal to $4\lambda$
Phase difference δ= $\frac{2\pi }{\lambda }\times △x$
​$\mathrm{given} \mathrm{path} \mathrm{difference} \mathrm{is} 4\mathrm{\lambda }$