Can i use all purpose flour instead of whole wheat flour?
You can. Use 7/8ths of the amount called for in the recipe, and expect a change in texture. Whole wheat flour bakes into a heavier and less airy product, as it is heavier by the cup and has proportionally less gluten than all-purpose flour. For cakes, it's best to select whole wheat cake flour.
It really depends on the recipe. Whole wheat flour is not as finely processed and has a different texture. Whole wheat includes bran, is higher in protein and needs more liquid. Generally it’s better to substitute no more than half the all purpose with whole wheat and a little more liquid.