681: The maturity of a river course is recognised by the presence of

(a) V-shaped valley

(b) Meanders

(c) Gorges

(d) High denudational power
682: The Himalayan Range is very rich in species diversity, Which one among the following is the most appropriate reason for this Phenomenon?

(a) It has a high rainfall that supports luxuriant vegetative growth

(b) It has less human interference

(c) Exotic and invasive species have riot been introduced in this region

(d) It is a confluence of different bio-geographical zones
Explanation:
The confluence of different bio-geographical zones like Mediterranean, Indo-Chinese etc. is the major reason for the rich species diversity of Himalayan Range. Hence option D is the answer.
683: Match List-I (New Names of the Countries) with List-II (Old Names of the Countries) and select the correct answer using the codes given below the Lists :

List-I List-II

(New Names ) (Old Names )

A. Benin 1. Nyasaland
B. Belize 2. Basutoland
C. Botswana 3. Bechuanaland
D. Malawi 4. British Honduras
5. Dahomey

Codes:

A B C D
(a) 3 1 2 4
(b) 5 4 3 1
(c) 3 4 2 1
(d) 5 1 3 4
Explanation:
Benin is the new name of Dohomey
Belize is the new name of British Honduras
Botswana is the new name of Bechuanaland
Malawi is the new name of Nyasaland
684: Caldera is a feature associated with

(a) Volcanoes

(b) Earthquakes

(c) Folding of rocks

(d) Faulting of mountains
685: Match List-I with List-II and select the correct answer using the codes given below the lists:

List I (City)

(A) Washinton D.C.
(B) Berlin
(C) Paris
(D) Madrid

List II (River)

1. River Manzanares
2. River Seine
3. River Spree
4. River Potomac

(A) 2 1 4 3
(B) 2 3 4 1
(C) 4 1 2 3
(D) 4 3 2 1
Explanation:
Washington D.C. - River Potomac
Berlin - River Spree
Paris - River Seine
Madrid - River Manzanares