$A$ convex mirror is used to form the image of a real object. Then tick the wrong statement.

Where should the light source (bulb) be placed in the reflector of a searchlight or torch so that the light rays travel over a long distance?

$(a)$ Why does a ray of light passing through the centre of curvature of a concave mirror after reflection get reflected back along the same path?
$(b)$ Why are convex mirrors commonly used as rear-view mirrors in vehicles?
$(c)$ $A$ pencil partly immersed in water in a glass tumbler appears to be displaced at the interface of air and water. Name the phenomenon of light responsible for it.

Which type of image cannot be obtained by a concave mirror?

Which of the following materials has maximum optical density?

Multiple images are formed by a thick plane mirror. Which of the following is the brightest of all the images?