Alkene series has the general formula of C_nH_2n. Propene is the second member of the alkene family and has C₃H₆ as the molecular formula.

Two functions performed by the testis in human beings are:
i) It  produces the male hormone, which is responsible for the secondary sexual changes in males.
ii) It produces sperms, required for fertilisation.

Ozone shields the surface of the earth from harmful ultraviolet (UV) rays.  UV rays are highly damaging to the organisms and cause skin cancers in human beings. 

Characteristics of the images formed by plane mirrors are:

i) The image formed is of the same size as that of the object.

ii) Images are formed behind the mirrors and are at the same distance from the mirror as that of the object.

iii) The virtual and erect image is formed.

iv) The images are laterally inverted. 

Forests are considered “biodiversity hot spots” because they have very high level of species richness and a high degree of endemism.

A person can effectively contribute towards the management of forests and wildlife by:

i) Using fewer products which are  derived directly from forests and wildlife such as wood, animal skin etc.

ii) Avoid discriminate cutting down of forest for the industrial purpose.