21: The waterfall "Victoria" is associated with the river
(a) Amazon
(b) Missouri
(c) St Lawrence
(d) Zambezi
22: Where does exchange of gases (O2 and CO2) take place in our lungs ?
(a) Alveoli
(b) Bronchi
(c) Pleura
(d) Trachea
23: Consider the following statements:
1. The Nuclear Security Summits are periodically held under the aegis of the United Nations.
2. The International Panel on Fissile Materials is an organ of International Atomic Energy Agency.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
24: The Second Round Table Conference was held in
(a) 1930
(b) 1931
(c) 1932
(d) 1935
25: There are 10 identical coins and each one of them has H engraved on its one face and T engraved on its other face. These 10 coins are lying on a table and each one of them has H face as the upper face.
In one attempt, exactly four (neither more nor less) coins can be turned upside down. What is the minimum total number of attempts in which the T faces of all the 10 coins can be brought to be the upper faces ?