If an image formed behind the concave mirror, the object distance is positive but if an image is formed in front of the mirror, the image distance is negative.

(I) Actually, meet or intersect with each other. (II) Actually, converge at a point. (III) Appear to meet when they are produced in the backward direction. (IV) Appear to diverge from a point.

If salivary amylase is lacking in the saliva, the process of starch digestion will get disturb as salivary amylase helps in digestion of starch.