Physics

              51. the term’ hydroponics’ is used to describe

                        (a) sound propagation under water

                        (b) cultivation of plants in water

                        (c)   a disease in which patient develops fear of water

                        (d) study of electronic devices which work under water

               52. Air is

                         (a) always a compound

                         (b) always a mixture

                         (c) A compounds in pollution –free zones

                         (d) a mixture in industrial zones

              53.  Ball bearings as used in bicycles, cars, etc, because

                        (a) the actual area of contact between the wheel and axle is increased

                        (b)  the effective area of contact between the wheel and axle increased

                        (c)  the effective area of contact between the wheel and axle is reduced

                       (d) None of the above statements is correct

              54.   rainbow is produced when sunlight falls on ropes of rain. Which of the following physical phenomena are responsible for this?

                    1. Dispersion

                    2. Refraction

                    3. Internal reflection

Select the correct answer using the codes given below

(a)    1 and 2

(b)   1 and 3

(c)    1 and 3

(d)    All of  these

          55. In dry cell (battery), which of the following are used as electrolytes?

(a)    Ammonium chloride and zinc chloride

(b)   Sodium chloride and calcium chloride

(c)    Magnesium chloride and zinc chloride

(d)   Ammonium chloride and Calcium chloride

          56. Conside the following phenomena

                   1.  Size of the sun at dusk

                   2.  Colour of the Sun at dawn

                    3.   Moon being visible at dawn

                    4.  twinkle of stars in the sky

                    5. Polestar belling visible in the sky

Which of the above are optical illusions?

(a)    1,2 and 3

(b)   3, 4 and 5

(c)    1, 2 and 4

(d)   2, 3  and 5

            57. A team of scientists at Brookhaven national Laboratory including those from India created the heaviest anti-matter (anti-helium nucleus.) What is / are the implication / implications of the creation of anti-matter?

1.       It will make mineral prospecting and oil exploration easier and cheaper.

2.       It will help probe the possibility of the existence of stars and galaxies made of anti-matter.

3.       It will help to understand the evolution of the universe.

Select the correct answer using the codes given below.

(a)    Only 1

(b)   2 and 3

(c)    Only 3

(d)   1, 2 and 3

          58. Electrically charged particles form space travelling at speeds of several hundred km/s can severely harm living beings if they reach the surface of the earth. What prevents them from reaching the surface of the Earth?

(a)    The earth’s magnetic field diverts them towards its poles

(b)   Ozone layer around the Earth reflects them back to outer space

(c)    Moisture  in the upper layers of atmosphere prevents them from reaching the surface of the Earth

(d)   None of the above

           59.  Nearly 30% of the solar radiations return back to the space without contributing anything to the Earth’s surface temperature. This amount of radiation is known as

(a)    Black body

(b)   Tropopause

(c)    Earth’s albedo

(d)   Mesopause

            60.  Consider the following metals

1.       Uranium

2.       Radium

3.       Plutonium

Which of these are used in making nuclear weapons?

(a)    1  and 2

(b)   1, 2 and 3

(c)    2  and 3

(d)   1 and 3

Answer:

1.       B

2.       C

3.       C

4.       D

5.       A

6.       A

7.       B

8.       A

9.       C

10.   D