26. A body weighs 250 N on the surface of the earth. How much will it weigh half way down to the centre of the earth ?      (1) 125 N              (2) 200 N      (3) 250 N              (4) 100 N 27. Six similar bulbs are connected as shown in the figure with a DC source of emf E and zero internal resistance.   The ratio of power consumption by the bulbs when (i) all are glowing and (ii) in the situation when two from section A and one from     section B are glowing, will be :       (1) 4 : 9                 (2) 9 : 4       (3) 1 : 2                 (4) 2 : 1 28. For a p...

21. Two similar thin equi-convex lenses, of focal length f each, are kept coaxially in contact with each other such that the focal length of the combination is  F1 . When the space between the two lenses is filled with glycerine (which has the same refractive index   ( m   = 1.5) as that of glass) then the equivalent focal length is  F2 . The ratio F1: F2 will be :  (1)  2 : 1                           (2) 1 : 2  (3) 2 : 3                           (4) 3 : 4 22. Increase in temperature of a gas filled in a container would lead to : (1) Increase in its mass (2) Increase in its kinetic energy (3) Decrease in its pressure (4) Decrease in intermolecular distance 23. An electron is accelerated through a potential difference of 10,000 V. Its de Broglie wavelength is,  (nearly)...

Parental factors and home environment found to play a role in student math abilities A pair of researchers at the University of Sussex has  found that the kind of relationship a child has with his or  her parents can have a major impact on how well they do  in learning math at school. In their paper published in the  journal  Royal Society Open Science , Danielle Evans  and Andy Field describe their study of data from an  ongoing research effort aimed at learning about how  children grow up in the U.K. and what they learned from it. The United Kingdom is in the midst of what the authors describe as a "maths crisis." Half of all adults in the U.K., they claim, have  math skills  no better than what would be expected of a child in kindergarten. Such deficiencies are seen as a threat to employment opportunities and give rise to higher rates of people living at the lower end of the economic spectrum. To better ...

16. If a recombinant DNA bearing gene for ampicillin resistance is transferred into E. Coli cells and the host cells are spread on agar plates containing amplicillin,then a)   Both transformed and untransformed recipient cells will die b)   Both transformed and untransformed recipient cells will grow c)   transformed recipient cells will grow and untransformed recipient cells will die d)   transformed recipient cells will die and untransformed recipient cells will grow 17. The figure below shows three steps (A,B,C) of polymerase chain reaction (PCR). Select the option giving correct identification together with what it represent?         a)   B- denaturation at a temperature of about 98   separating the two DNA strands. b)   A- denaturation at a temperature of about 50 c)   C- extension in the presence of heat stable DNA polymerase. d)   A- ...

11.Gel electrophoresis is used for          a)     Construction of recombinant DNA by joining with cloning vectors          b)     Isolation of DNA molecules          c)     Cutting of DNA into fragments      d) Separation of DNA fragments according to their size 12. Plasmids are extrachromosomal circular DNA molecules a)   Which have their own point of replication and can replicate independently b)   Which have their own point of replication and cannot replicate independently c)   Which do not have on point of replication and cannot replicate independent of bacterial chromosome DNA. d)   None of these 13. Recombinant DNA is achieved by cleaving the pro-DNAs by which of the following enzyme? a)   Legase b)   Primase c)   Exonucleases d)   Restriction endonuclease...

6) In which of the following devices, the eddy current effect is not used?    (1)     Induction furnace    (2)    Magnetic braking in train    (3)    Electromagnet   (4)   Electric heater EXPLANATION: Electric heater does not involve Eddy currents.  It uses Joule's heating effect. 7) A soap bubble, having radius of 1 mm, is blown from a detergent solution having a surface tension of 2.5 × 10 –2 N/m. The pressure inside the bubble equals at a point Zo  below the free surface of water in a container. Taking g = 10 m/s 2 , density of water =10 3 kg/m 3 , the value of Zo  is :    (1)    100 cm    (2)    10 cm   (3)   1 cm    (4)    0.5 cm EXPLANATION: 8) Which colour of the light has the longest wavelength?   (1)   Red    (2)    Blue    (3) ...