17 Which of the following phenomenon gives evidence of the molecular motion 1 Brownian motion 2 Diffusion 3 Evaporation 4 All of these 18 Volume versus temperature graph of two mole of helium gas is as shown in figure The ratio of change in internal energy and the work done by the gas in process 1 2 is 3 11 2 20 3 5 27 2 1 19 The efficiency of the reversible heat engine is 1 and that of irreversible heat engine is n Which of the following is correct 1 n 1 and n 1 2 1 3 n 1 and n 1 4 1 1 20 Temperature of a body is slightly more than the temperature of the surrounding 0 its rate of cooling R versus temperature of body 0 is plotted its shape would be as per Newton s of cooling R 3 2 3 2 73 4 21 The specific heat of substance varies with temperature 7 as S 0 20 1 47 cal gm C Heat required to raise the temperature of 2 gm of the substance from 5 C to 25 C is T is in C 1 848 cal 3 336 cal 22 Expansion of liquid on heating is different from that solids since expansion of liquid is 24 1 More than solids because molecular spacing in them is less 2 More than solids because molecular spacing in them is more 3 Less than solid because molecular spacing in them is more 4 Less than solids because molecular spacing in them is less 23 A body of mass 25 g is under water at a depth of 50 cm If the specific gravity of material of body is 5 the work necessary to lift the body slowly to the surface is g 9 8 m s 1 980 x 105 erg 3 980 x 10 erg ole Charge Q is distributed on two metallic spheres having radii R and 3R such that both spheres have equal charge density then charge on smaller sphere 1 2 424 cal 4 672 cal 2 3 Ca Charge is distributed non uniformly in a volume of solid insulating sphere of radius a such that volume charge density p varies with distance from the centre r as p r Cr r a and C is constant Magnitude of electric field strength outside the sphere at a distance r from centre will be 55 5 Ca 2 9 8 x 105 erg 4 98 x 105 erg 45 4 Gla 10Q