List two functions of ovary of human female reproductive system.

(a) Define focal length of a spherical lens.

(b) A divergent lens has a focal length of 30 cm. At what distance should an object of height 5 cm from the optical center of the lens be placed so that its image is formed 15 cm away from the lens? Find the size of the image also.

(c) Draw a ray diagram to show the formation of image in the above situation.

Write the name and structure of an aldehyde with four carbon atoms in its molecule.

In a food chain of frog, grass, insect and snake, assign trophic level of frog.

The refractive indices of glass and water with respect to air are 3/2 and 4/3 respectively. If speed of light in glass is 2 x 10⁸m/s, find the speed of light in water.