3936: Which one of the following is the best description of the term 'ecosystem'?
(a) A community of organisms interacting with one another.
(b) That part of the Earth which is inhabited by living organisms.
(c) A community of organisms together with the environment in which they live
(d) The flora and fauna of a geographical area
3937: Consider the following statements :
Chlorofluorocarbons, known as ozone-depleting substances, are used
1. in the production of plastic foams
2. in the production of tubeless tyres
3. in cleaning certain electronic components
4. as pressurizing agents in aerosol cans
Which of the statements given above is/are correct?
(a) 1, 2 and 3 only
(b) 4 only
(c) 1, 3 and 4 only
(d) 1, 2, 3 and 4
3938: Isotopes of the same element differ in the number of:
(a) Protons
(b) Neutrons
(c) Electrons
(d) Positrons
3939: A community of people called Manganiyars is well-known for their
(a) martial arts in North-East India
(b) musical tradition in North- West India
(c) classical vocal music in South India
(d) pietra dura tradition in Central India
3940: The memory of a computer is commonly expressed in terms of Kilobytes or Megabytes. A byte is made up of
(a) eight binary digits
(b) eight decimal digits
(c) two binary digits
(d) two decimal digits