What is the focal length of a convex lens having power $+5.0 \,D$?

Which of the following statements is true regarding a real image of an object?

Where is the object placed in a compound microscope?

In Section $I$, the magnification of the image obtained by placing an object at various distances in front of a concave mirror is mentioned, and in Section $II$, the type and size of the image are mentioned. Which of the following is the correct pair connecting Section $I$ and Section $II$?

Section $I$	Section $II$
$1.$ Magnification $(-1)$	$a.$ Real and enlarged
$2.$ Magnification $(+5)$	$b.$ Real and same size as object
$3.$ Magnification $(-5)$	$c.$ Real and diminished
$4.$ Magnification $(-0.5)$	$d.$ Virtual and enlarged

In torches,searchlights,and headlights of vehicles,the bulb is placed:

State the sign convention used to measure the length of the image and the object.