Given, $P=+5 D$We have,$\; \text{ Power, } \; P\;=\;\frac{1}{f(\; \text{ in meter } \;)}$$+5\;=\;\frac{1}{f}$$f\;=\;\frac{1}{5} \text{ m}$$\;=\;\frac{100}{5}=20 \text{ cm}$ Focal length, $f=20 \text{ cm} (or +20 \text{ cm}$ ).Since, focal length of the lens is positive.Therefore, the nature of lens is convex.Same size and inverted image is formed whenMagnification, $m=-1$Also,$m\;=\;\frac{v}{u}$$v\;=-u$From the lens formula,$\;\frac{1}{v}-\;\frac{1}{u}=\;\frac{1}{f}$ $-\;\frac{1}{u}+\;\frac{1}{u}\;=\;\frac{1}{f}$$\;\frac{-2}{u}\;=\;\frac{1}{f}$$u\;=-2 f$$u\;=-2 \times 20 \;\; [ \because f=20 \text{ cm} ]$$\;=-40 \text{ cm} .$