TEST-11(Solution) TOPIC : HEAT COMPLETE 2400 = m 80 [ Q = ml]

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Gervais Derrick Ferguson
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1 entigrade emperature (º) emperature () ES-(Solution) OI : HE OMLEE 400 = m 80 [Q = ml] Q. If specific heat of a substance is infinite, it means- () Heat is given out () Heat is taken in () No change in temperature takes place whether heat is taken in or given out () ll of the above [] Q = m.c. c = Q m. ;when = 0 c = Q. wo spheres made of same substance have diameters in the ratio :. heir thermal capacities are in the ratio of - () : () : 8 () : 4 () : [] Q. 80 gm of water at 0º are poured on a large block of ice at 0º. he mass of ice that melts is () 0 gm () 80 gm () 600 gm () 50 gm [] Q.4 he graph shown in figure is a plot of temperature of a body in degree elsius and degree Fahrenheit. hen - 00º º F ºF Fahrenheit () Slope of line is 9/5 () Slope of line is 5/9 () Slope of line is /9 () Slope of line is /9 [] Q.5 80 gm of water at 0 is poured on a large block of ice at 0. he mass of ice that melts is - () 60 gm () 80 gm () 40 gm () 0 gm [] Heat released by water Q = 80 0 = 400 cal Mass of Ice melt (i) m = 400 = 0 gm 80 Q.6 Which of the substances, or has the highest specific heat? he temperature vs time graph is shown - ime (t) () () () () ll have equal specific heat [] Q.7 solid substance is at 0º. o this substance heat energy is supplied at a constant rate. hen temperature versus time graph is as shown in the figure. he substance is in liquid state for the portion (of the graph) - () ime () () E () EF [] Q.8 mixture of 50 gm of water and 00 gm of ice at 0 is kept is calorimeter of water equivalent 50 gm. If 00 gm of steam at 00 is passed through the mixture then the final amount of water in the mixture will be (Latent Heat of ice = 80 cal/gm, latent Heat of vaporisation of water = 540 cal/gm and specific heat of water = cal/gm ) - () 450 gm () 6 gm () 57 gm () 650 gm E F age of 7

2 [] Heat required by (ice +water + calorimeter) to raise upto 00º = [00 80] + [500 00] calorie Let "m" gm of steam condenses, = m 540 m gm So final amount of water = = 57gm Q.9 wo solid bodies of equal masses are heated at the same rate under identical condition. he change is temperature is shown graphically as a function of time. he ratio of specific heat in solid form should be (S /S ) - emp ime (sec) () 4/ () /8 () 5/8 () /4 [] Let "" is the rate at which heat is supplied to both &. For : (6) = m (40) () For : (4) = m (70) () From () & (), 6 = 4 (40) (70) 40 = = 60 8 Q.0 ontainer below are filled with three different gases as shown. iston is made to oscillate in below three cases. ime eriod of oscillation is,,. hen- N m He m SO m mono > di > poly Q. partition divides a container having insulated walls into two compartments I and II. he same gas fills the two compartments (shown in figure). he ratio of the number of molecules in compartments I and II is,v, I II,V, () : 6 () 6 : () 4 : () : 4 NI I.VI II [] : 4 NII I II.VII Q. Jar filled with gas characterized by parameter,v and and another jar filled with a gas with parameter, V/4 and. he ratio of the number of molecules in jar to those in jar is- () : () : () : () 4 : [] V N = K N N V K 4 = = K (V / 4) Q. One mole of ideal monoatomic gas ( = 5/) is mixed with two mole of diatomic gas ( = 7/5). What is for mixture? () / () 5 () > > () > > () > > () > > [] ime period of oscillation of piston is r where = p / v adiabatic exponent mono = 5/ ; di = 7/5; poly = 4/ 9 () mix = p v p v () 4/ [] age of 7

3 = 5 7 R R 5 R R 9 = Q.4 he absolute temperature of a gas is increased times. he root mean square velocity of the molecule will become () times () 9 times () ( ) times () times [] Q.5 he correct curve between V/ and /V for a gas at constant pressure is () V/ () V/ /V () V/ () V/ /V /V /V [] Q.6 ressure versus temperature graph of an ideal gas is as shown in figure. ensity of the gas at point is 0. ensity at will be 0 0 () () 0 Q.8 triatomic molecule can be modelled as three rigid sphere joined by three rigid rods forming an triangle. onsider a triatomic gas consisting such molecule. If gas performs 0 J work when it expands under constant pressure the heat given to gas is - () 60 J () 0 J () 45 J () 0 J [] Q = W R f = R (f = degree of produce) = 4R Q = 4W = 0 J Q. 9 In the following cyclic process is V he above process in the - coordinates is given as () () () () 4 0 () 0 [] Q.7 mixture of H and O gases is filled in a vessel at constant temperature. he ratio of rootmean-square speeds of the molecules of these gases will be () : () : () : () 4 : [] age of 7

4 () [] Q.0 he temperature-entropy diagram of a reversible engine cycle is given in the figure. Its efficiency is - [IEEE-005] 0 0 S 0 S 0 S () / () /4 () / () / [] Q. system goes from to via two processes I and II as shown in figure. If U and U are the changes in internal energies in the processes I and II respectively, then [IEEE-005] II I () U = U () relation between U and U can not be determined () U > U () U < U V [] Q. he work of 46 kj is performed in order to compress one kilo mole of a gas adiabatically and in this process the temperature of the gas increases by 7º. he gas is - (R = 8. J mol K ) [IEEE 006] () a mixture of monoatomic and diatomic () monoatomic () diatomic () triatomic [] Q. arnot engine, having an efficiency of = /0 as heat engine, is used as a refrigerator. If the work done on the system is 0 J, the amount of energy absorbed from the reservoir at lower temperature is [IEEE 007] () 99 J () 90 J () J () 00 J [] Q.4 When a system is taken from state i to state f along the path iaf, it is found that Q = 50 cal and W = 0 cal. long the path ibf Q= 6 cal. W along the path ibf is- [IEEE 007] () 6 cal a i f b () 6 cal () 66 cal () 4 cal [] Q.5 n ideal gas is taken from the state (pressure, volume V) to the state (pressure /, volume V) along a straight line path in the V diagram. Select the correct statement (s) from the following [II 9] () he work done by the gas in the process to exceeds the work that would be done by it if the system were taken from to along an isotherm () In the V diagram, the path becomes a part of a parabola () In going from to, the temperature of the gas first increases to a maximum value and then decreases () ll of these [] Q.6 Starting with the same initial conditions, an ideal gas expands from volume V to V in three different ways. he work done by the gas is W if the process is purely isothermal, W if purely isobaric and W if purely adiabatic. hen [II 000] () W > W > W () W > W > W () W > W > W () W > W > W [] Q.7 n ideal gas is taken the cycle, as shown in the figure. If the net heat supplied to age 4 of 7

5 the gas in the cycle is 5 J, the work done by the gas in the process is - [II 00-0] () 5 J V (m ) 0 (N/m ) () 0 J () 5 J () 0 J [ Q.8 hree rods made of the same material and having the same cross section have been joined as shown in the figure. Each rod is of the same length. he left and right ends are kept at 0º and 90º respectively. he temperature of the junction of the three rods will be - 90º 0º H (in kj) () J/kg/º 45º (in º) () 0.5 J/kg/º () kj/kg/º () 0.5 kj/kg/º [] Slope of H vs graphs give heat capacity. Specific heat capacity = heat capacity mass tan 45º kj/kg/º = 0.5 kj/kg/º 90º () 45º () 60º () 0º () 0º [] Q.9 Five rods of same dimensions are arranged as shown in the figure. hey have thermal conductivities K, K, K, K 4 and K 5. When points and are maintained at different temperatures. No heat flows through the central rod if - K K K 5 K K 4 () K = K 4 and K = K () K K 4 = K K () K K = K K 4 K K () K K [] Q.0 solid of mass kg is heated and H (Heat given) vs (change in temperature) is plotted. Specific heat of solid is 4 Q. Mechanism of heat-transfer involved in freezing of lakes in colder region - () onduction only () Radiation only () onvection only () None of these [] Water of lake gets cooled by conduction till 4º after that it is cooled by conduction through ice. Q. cylinder of radius R made of material of thermal conductivity K is surrounded by a cylindrical shell of inner radius R and outer radius R made of a material of thermal conductivity K. he two ends of the combined system are maintained at two different temperature. What is the effective thermal conductivity of the system? () K + K () KK K K K 8K () 9 () 8 K K [] 9 age 5 of 7

6 = + R R R eq E K eq (9R ) K R = K + L L K 8K K eq = 9 8 R L Q. ring consisting of two parts and of same conductivity K carries an amount of heat H. he part is now replaced with another metal keeping the temperatures and constant. he heat carried increases to H. What should be the conductivity of the new part? (Given = ) () 7 K () K () 5 K () K [] K ( ) H + H = K ( ) + 4 = K l l l ( ) In later case 7K K ' H = H H = ( ) = ( ) l l K = 7 K Q.4 sphere of surface temperature is in thermal equilibrium with its environment. Which of the curves gives the energy E radiated by sphere versus time t () () () () 4 [] Q.5 he rate of loss of heat by radiation from a body at 400º is R. he radiation from it when the temperature rises to 800º? () R () 6R [] () 4R 4 () None of the above Q.6 body cools from 50.0º to 49.9º in 5s. How long will it take to cool from 40.0º to 9.9º? ssume the temperature of the surrounding to be 0.0º and Newton s law of cooling to be valid - ().5 s () 0 s [] () 0 s () 5 s Q.7 second s pendulum clock having steel wire is calibrated at 0º. When temperature is increased to 0º, then how much time does the clock lose or gain in one week? [ steel =. 0 5 (º) ] : () 0.68 s ().66 s () 6.8 s () 6.8 s [] Q.8 If the length of a cylinder on heating increases by %, the area of its base will increase by t () 0.5% () % () % () 4% [] age 6 of 7

7 ensity ensity ensity ensity Q.9 solid ball of metal has a spherical cavity inside it. If the ball is heated, the volume of the cavity will () Increase () ecrease () Remains unchanged () Have its shape changed [] Q.40 If are linear, superficial and cubical expansivity of a solid, then () : : = : : () : : = : : () : : = : : () : : = : : [] Q.4 he volume of a solid decreases by 0.6% when it is cooled through 50º. Its coefficient of linear expansion is () K () K () K () K [] () = () = () = 4 () = [] Q.44 wo rods of lengths and are made of materials whose coefficient of linear expansions are and. If the difference between two lengths is independent of temperature () () = () () Q. 45 If a bimetallic strip is heated, it will [] () bend towards the metal with lower thermal expansion coefficient () bend towards the metal with higher thermal expansion coefficient () not bend at all () twist itself into a helix [] Q.4 Which of the following curve represent variation of density of water with temperature best () () emp. emp. () () emp. emp. [] Q.4 hree rods of equal length are joined to form an equilateral triangle. is midpoint of. he coefficient of linear expansion is for, and for and. If the distance remains constant for small changes in temperature age 7 of 7

HEAT & THERMODYNAMICS

HEAT & THERMODYNAMICS Einstein lasses, Unit No. 0, 03, ardhman Ring Road laza, ikas uri Extn., Outer Ring Road New Delhi 0 08, h. : 9369035, 857 HT HEAT & THERMODYNAMIS Syllabus : HEAT Heat, temperature, thermal expansion;