831: There are two identical red, two identical black and two identical white balls. In how many different ways can the balls be placed in the cells (each cell to contain one ball) shown below such that balls of the same colour do not occupy any two consecutive cells?
(a) 15
(b) 18
(c) 24
(d) 30
832: Which feature of some, species of blue-green algae helps promote them as bio-fertilizers?
(a) They convert atmospheric methane into ammonia which the crop plants can absorb readily
(b) The induce the crop plants to produce the enzymes which help convert atmospheric nitrogen to nitrates
(c) They have the mechanism to convert atmospheric nitrogen into a form that crop can absorb readily
(d) The induce the roots of the crop plants to absorb the soil nitrates in larger quantities
833: Which of the following periods can be considered as the era of mass revolution?
(a) 1856-1885 A.D.
(b) 1757-1857 A.D.
(c) 1920-1947 A.D.
(d) 1901-1919 A.D.
834: The most important strategy for the conservation of biodiversity together with traditional human life is the establishment of
(a) biosphere reserves
(b) botanical gardens
(c) national parks
(d) wildlife sanctuaries
835: In the year 2007, an earthquake led to massive radioactive water leakage in the largest nuclear plant in the world. In which country did it occur?
(a) Canada
(b) Japan
(c) Germany
(d) USA