What is the lens placed near the eye in a compound microscope called?

$A$ pencil when dipped in water in a glass tumbler appears to be bent at the interface of air and water. Will the pencil appear to be bent to the same extent,if instead of water we use liquids like kerosene or turpentine? Support your answer with reason.

Where should an object be placed in front of a concave mirror to obtain an inverted and magnified image?

Copy the figure and show the image formation with the help of rays.

What does positive magnification mean?

$A$ virtual image cannot be focused on a screen. Yet when we see a virtual image,we obviously bring it to the screen that is the retina of our eyes. Is this a contradiction?