Study the following figure in which a student has marked the angle of incidence (), angle of refraction (), angle of emergence (), angle of prism () and the angle of deviation (). The correctly marked angles are:

To determine the approximate focal length of the given convex lens by focussing a distant object (say, a sign board), you try to focus the image of the object on a screen. The image you obtain on the screen is always:

Select from the following the best experimental set-up for tracing the path of a ray of light passing through a rectangular glass slab:

What do you observe when you drop a few drops of acetic acid to a test tube containing:

(i) phenolphthalein

(ii) distilled water

(iii) universal indicator

(iv) sodium hydrogen carbonate powder

Draw a labeled diagram to show that particular stage of binary fission in amoeba in which its nucleus elongates and divides into two and a constriction appears in its cell membrane.