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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
A brass rod of length `50 cm` and diameter `3.0 cm` is joined to a steel rod of the same length and diameter. What is the change in length of the combined rod at `250^(@)C`, if the original length are at `40.0^(@)C`? (Coefficient of linear expansion of brass `=2.0 xx 10^(-5)//^(@)C, steel = 1.2 xx 10^(-5)//^(@)C`A. `0.27 cm`B. `0.34 cm`C. `0.21 cm`D. `0.18 cm` |
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Answer» Correct Answer - B Change in temperature of each rod, `Delta T = 250 -40 = 210^(@)C` Clearly change in length of the brass bar `Delta L_(S)=alpha_(S)Ldelta T = (1.2 xx 10^(-5)) xx 50 xx 210 = 0.126 cm` Since the ends of the rod are free to expand, change in the length of the combined rod `Delta L = Delta L_(b) + Delta L_(s) = 0.21 + 0.13 = 0.34 cm`. |
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| 152. |
Match the following. A. `A - r, B - q, C - p, D -s`B. `A - r, B - s, C - q, D - p`C. `A - q, B - p, C - s, D - r`D. `A - p, B - q, C - r, D - s` |
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Answer» Correct Answer - B Conversion of a liquid into solid is fusion. `A rarr r` Conversion of a liquid into vapour is vaporisation. `B rarr s` Conversion of a solid into vapour directly is sublimation. `C rarr q` Melting of ice caused by pressure is regelation. `D rarr p` |
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| 153. |
Which of the following statement is correct ?A. The triple point of water is `253.16 K`.B. Burns from steam are less severe than those from boiling water.C. Ethyl alcohol expands less than mercury for the same rise in temperature.D. When fully inflated ballon is immersed in cold water, it will contract. |
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Answer» Correct Answer - D The triple point of water is `273.16` K. Hence, option (a) is an incorrect statement. Burns from steam are more serious than those from boiling water. Hence option (b) is an incorreect statement. The coefficient of volume expansion of mercury and ethyl alcohol are `18.2 xx 10^(-5) K^(-1)` and `110 xx 10^(-5) K^(-1)` respectively. Since coefficient of volume expansion for ethyl alcohol is more than mercury therefore, ethyl alcohol expands more than mercury for the same rise in temperature. Hence option (c ) is an incorrect statement. When fully inflated ballon is immersed in cold water it would start shrinking due to contraction of the air inside. Hence, option (d) is incorrect statement. |
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| 154. |
When `1.5 kg` of ice at `0^(@)C` mixed with `2` kg of water at `70^(@)C` in a container, the resulting temperature is `5^(@)C` the heat of fusion of ice is (`s_("water") = 4186 j kg^(-1)K^(-1))`A. `1.42 xx 10^(5) j kg^(-1)`B. `2.42 xx 10^(5) j kg^(-1)`C. `3.42 xx 10^(5) j kg^(-1)`D. `4.42 xx 10^(5) j kg^(-1)` |
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Answer» Correct Answer - C Heat lost by water `= m_(w)s_(w) (T_(i) - T_(f))` `= 2 xx 4186 xx (70-5) = 544180 j` Heat required to rise temperature of melt ice `= m_(i)L_(f) = 1.5 xx L_(f)` Heat required to rise temperature of ice `= m_(i)s_(w) (T_(f) - T_(0)) = 1.5 (4186) xx (5-0^(@)) = 31395 j` By the principle of calorimetry Heat lost = heat gained `544180 = 1.5 L_(f) + 31395` `:. L_(f) = (512785)/(1.5) = 341856.67 = 3.42 xx 10^(5) j kg^(-1)` |
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| 155. |
`4 g` hydrogen is mixed with 11.2 litre of He at (STP) in a container of volume 20 litre. If the final temperature is `300 K`, find the pressure. |
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Answer» `4g` hydrogen `=2` moles hydrogen `11.2` litre He at `STP = (1)/(2)` mole of He `P = P_(H) + P_(He) = (n_(H) + n_(He))(RT)/(V)` `= (2 + (1)/(2))(8.31 xx (300))/((20 xx 10^(-3))) = 3.12 xx 10^(5) N // m^(2)` |
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| 156. |
A cube of ice is placed on bimetallic strip at room temperature as shown in the figure. What will happen if the upper strip of iron and the lower strip of copper? A. Ice moves downwardB. Ice moves upwardC. Ice remains in restD. None of the above |
| Answer» Correct Answer - A | |
| 157. |
To withstand the shapes of concave mirrors against temperature variations used in high resolution telescope, they are made ofA. quartzB. flint glassC. crown glassD. combination of flint and silica |
| Answer» Correct Answer - A | |
| 158. |
If accidently the calorimeter remained open to atmosphere for some time during the experiment, due to which the steady state temperature comes out to be `30^(@)C`, then total heat loss to surrounding during the experiment, is (Use the specific heat capacity of the liquid from previous questions).A. `20 kcal`B. `15 kcal`C. `10 kcal`D. `8 kcal` |
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Answer» Correct Answer - B Heat given by the sphere `=(1000)(1//2)(80-30) = 25000 cal` Heat absorbed by the water calomiter system `=(900)(1)(30-20)+(200)(1//2)(30-20)` `=10,000 cal` So heat loss to surrounding =`15000 cal`. |
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| 159. |
The linear expansion of a solid depends onA. its original massB. nature of the material and temperature difference.C. the nature of the material onlyD. pressures |
| Answer» Correct Answer - B | |
| 160. |
A long cylindrical metal vessel of volume `V` and coefficient of linear expansion `alpha` contains a liquid. The level of liquid has not changed on heating. The coefficient of real expansion of the liquid is.A. `(V - alpha)/(V)`B. `(V + alpha)/(V)`C. `(V)/(V - alpha)`D. `3alpha` |
| Answer» Correct Answer - D | |
| 161. |
Identify the correct statements from the following: (a) The apparent expansion of liquid depends the expansion of material of the container (b) The real expansion of the liquids depends on the density of the liquid. (c) The expansion of liquid with respect to the container is called the apparent expansionA. Only `a` & `b` are tureB. Only `b` & `c` are tureC. `a,b` & `c` are tureD. Only a & `c` are true |
| Answer» Correct Answer - C | |
| 162. |
Assertion : The coefficient of real expansion of the liquid is independent of nature of container.A. If both assertion and reason are true and reason is the correct explanation of assertionB. If the assertion and reason are true but reason is not the correct explanation of assertion.C. If assertion is true but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - A Coeffiecient of real expansion `gamma_(r)=gamma_(a)+gamma_(v)` Hence, `gamma_(v)` is coefficent of cubical expansion of vessel (container) Thus, real expansion coefficient depends on nature of vessel. |
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| 163. |
In an insulated vessel, 250 g of ice at `0^(@)C` is added to 600 g of water at `18^(@)C` (a) What is the final temperature of the system? (b) How much ice remains when the system reaches equilibrium? Useful data: Specific heat capacity of water: 4190 K/K.kg Speicific heat capacity of ice: 2100J/K.kg Latent heat of fusio of ice: `3.34xx10^(5)J//kg` |
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Answer» `Q_("required")=mL` `=(250xx10^(-3))xx3.34xx10^(5)` `=8.35xx10^(4)J`. Heat available from water is `Q_("available")=MCDeltaT=600xx10^(-2)xx4190xx1187` `=4.525xx10^(4)J`. (a) As heast available is not sufficient to melt ice, final temperature is zero. (b) the amount of ice that will melt to bring down the temperature of water from `18^(@)C` to `0^(@)C` is calculated as shown. `Q_("available")=m_(ice)xxL_(ice)` `4.525xx10^(4)=mxx3.34xx10^(5)` `impliesm_(ice)=135xx10^(-1)kg~~135g`. ltBrgt So, ice remaining=250-135 =115g |
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| 164. |
The liquid whose coeffcient of real expansion is equal to `1.5` times the coefficient of areal expansion of container and heated then the level of the liquid taken in the containerA. risesB. fallsC. remain sameD. first rises and then falls |
| Answer» Correct Answer - C | |
| 165. |
Coefficient of areal expansion of a solid is `2xx10^(-5).^(@)C^(-1)`. Calculate its coefficient of linear expansion. |
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Answer» `becausebeta=2alpha` `alpha=1.0xx10^(-5).^(@)C^(-1)` |
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| 166. |
A `250cm^3` glass bottle is completely filled with water at `50^@C`. The bottle and water are heated to `60^@C`. How much water runs over if: a. the expansion of the bottle is neglected: b. the expansion of the bottle is included? Given the coefficient of areal expansion of glass `beta=1.2xx10^(-5)//K` and `gamma_("water")=60xx10^(-5)//^@C`.A. `B.C.D. |
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Answer» Water overflown `=` (final volume of water `-` (final volume of bottle) (a) If the expansion of bottle is neglected: volume of water over flown `Delta_(1) = 250(1 + gamma_(1)theta) - 250 = 250 xx gamma_(1)theta` `= 250 xx 60 xx 10^(-5) xx 10 = 1.5cm^(3)` (b) If the bottle (glass) expands: volume of water over flown `DeltaV_(2) = 250(gamma_(1) - gamma_(2))theta`, where `gamma_(g) = (3beta)/(2) = 1.8 xx 10^(-5) //^(@)C` `= 250(58.2 xx 10^(-5)) xx (60 - 50) = 1.455 cm^(3)` |
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| 167. |
A faulty thermometer has `90.5^(@)C` and `0.5^(@)C` as upper and lower fixed points respectively. What is the correct temperature if this faulty thermometer reads `15.5^(@)C`A. `16.67^(@)C`B. `16^(@)C`C. `15^(@)C`D. `15.5^(@)C` |
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Answer» Correct Answer - A `(C - 0)/(100) = (X - L)/(U - L)` |
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| 168. |
A cylinder contained `10kg`of gas at pressure `10^(7) N / m^(2)`. The quantity of gas taken out of cylinder if final pressure is `2.5 xx 10^(6) N//m^(2)` is (Assume temperature of gas is constant)A. ZeroB. `7.5 Kg`C. `2.5 Kg`D. `5 Kg` |
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Answer» Correct Answer - B `P prop rho, rho prop m` When temperature and volume are constant `P prop m` |
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| 169. |
The volume of a metal sphere increases by `0.24%` when its temperature is raised by `40^(@)C` . The coefficient of linear expansion of the metal is .......... `.^(@)C`A. `2 xx 10^(5).^(@)C^(-1)`B. `6 xx 10^(-5).^(@)C^(-1)`C. `18 xx 10^(-5).^(@)C^(-1)`D. `1.2 xx 10^(-5).^(@)C^(-1)` |
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Answer» Correct Answer - A From, `V_(T) = V_(0)(1+gammaDeltaT)` `rArr (V_(T) -V_(0))/(V_(0)) = gammaDeltaT` `(0.24)/(100) = gamma40 .^(@)C` `gamma = (0.24)/(100 xx 40) = 6 xx 10^(-5) .^(@)C^(-1)` Coefficient of linear expansion, `alpha = (gamma)/(3) = (6 xx 10^(-5))/(3) = 2 xx 10^(-5) .^(@)C^(-1)` |
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| 170. |
A solid sphere of radius `r` and mass `m` is spining about a diameter as axis with a speed `omega_(0)`. The temperature of the sphere increases by `100^(0)C` without any other disturbance. If the coefficient of linear expansion of material of sphere is `2 xx 10^(-4 //0) C`, the ratio of angular speed at `100^(0)C` and `omega_(0)` isA. `1:1`B. `1:1.04`C. `1.04:1`D. `1:1.02` |
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Answer» Correct Answer - B `I_(1)omega_(1)=I_(2)omega_(2),R_(1)^(2)omega_(1) = R_(2)^(2)omega_(2)` `(omega_(2))/(omega_(1)) = ((R_(2))/R_(1))^(2) = (1)/(1 + alphaDeltat)^(2)` |
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| 171. |
At what temperature the Fahrenheit and kelvin scales of temperature give the same reading ?A. `theta = -40`B. `theta = 40`C. `theta = 574.25`D. `512.45` |
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Answer» Correct Answer - C `(T_(F)-32)/(180) = (T_(K)-273)/(100)` `(theta-32)/(180) = (theta-273)/(100) rArr 5 theta-32 xx 5 = 9 theta - 273 xx 9` `= theta = 574.25`. |
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| 172. |
At what temperature the Fahrenheit and kelvin scales of temperature give the same reading ?A. `-40`B. `313`C. `574.25`D. `732.75` |
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Answer» Correct Answer - C `((F - 32)/(180) = (K - 273)/(100))` But `F = K = x` |
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| 173. |
For measuring temperature near absolute zero, the thermometer used isA. thermoelectric termometerB. radiation thermometerC. magnetic thermometerD. resistance thermometer |
| Answer» Correct Answer - C | |
| 174. |
A pendulum clock, made of a material having coefficient of linear expansion `alpha=9xx10^(-7)//.^(@)C` has a period of 0.500 sec at `20^(@)C`. If the clock is used in a climate where temperature averages `30^(@)C`, what correction is necessary at the end of 30 days to the time given by clock?A. `11.66s`B. `3.88s`C. `0.100s`D. `2.0s` |
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Answer» Correct Answer - A |
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| 175. |
As the temperature is increased, the period of a pendulumA. increases as its effective length increases even through its centre of mass still remains at the cenre of the bobB. decreases as its effevtive length increases even though its centre of mass still remains at the centre of the bobC. increases as its effective length increases due to shifting to centre of mass bellow the centre of the bobD. decreases as its effective length remain same but the centre of mass shifts above the centre of the bob |
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Answer» Correct Answer - A `(DeltaT)/(T) = (1)/(2)alphaDeltatheta` |
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| 176. |
`4 gm` of steam at `100^(@)C` is added to `20 gm` of water at `46^(@)C` in a container of negligible mass. Assuming no heat is lost to surrounding, the mass of water in container at thermal equilibrium is. Latent heat of vaporisation `= 540 cal//gm`. Specific heat of water `=1 cal//gm-^(@)C`.A. `18 gm`B. `20 gm`C. `22 gm`D. `24 gm` |
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Answer» Correct Answer - C Heat released by steam in conversion to water a `100^(@)C` is `Q_(1)=mL=4xx540=2160 cal`. Heat required to raise temperature of water from `46^(@)C` to `100^(@)C` is `Q_(2) = mS Delta theta = 20xx1xx54=1080J` `Q_(1) gt Q_(2) and (Q_1)/(Q_2) =2` Hence all steam is not converted to water only half steam shall be converted to water Final mass of water =`20+2=22gm`. |
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| 177. |
A vessel contains a liquid filled with `1//10`th of its volume. Another vessel contains same liquid upto `1//8`th its volume. In both cases the volume in empty space remains constant at all temperatures. Then the ratio of coefficient of linear expansions of the two vessels isA. `2:5`B. `5:2`C. `4:5`D. `5:4` |
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Answer» Correct Answer - C `V_(1) = (V)/(10),V_(2)=(V)/(8) , V_(1)gamma_(1) = V_(g)gamma_(g)` |
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| 178. |
Two metal strips that constitue a thermostat must necessarily differ in theirA. MassB. LengthC. ResistivityD. Coefficient of linear expansion |
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Answer» Correct Answer - D Thermost is used in electric apparatus like refrigerator, iron etc. For automatic cut off. Therefore, for metallic strips to bend on heating their coefficient of linear expansion should be different. |
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| 179. |
Assertion : If thermal conductivity of a rod is `5`, then its thermal resistively is `0.2` Reason : Thermal conductivity `= (1)/("thermal resistivity")`A. If both assertion and reason are true and reason is the correct explanation of assertionB. If the assertion and reason are true but reason is not the correct explanation of assertion.C. If assertion is true but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - A Thermal resistivity = `(1)/("thermal condctivity")` `=1/5=0.2`. |
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| 180. |
Assertion : The melting point of ice decreases with increase of pressure Reason : Ice contract on melting.A. If both the assertion and reason are true and reason is the correct explanation of the assertion.B. If both the assertion and reason are true but the reason is not correct explanation of the assertion.C. If the assertion is true but the reason is falseD. If the both the assertion and reason are false. |
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Answer» Correct Answer - A With rise in pressure, melting point of ice decreases. Also ice contracts on melting. |
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| 181. |
Assertion : Perspiration from human body helps in cooling the body. Reason : A thin layer of water on the skin enhances its emissivity.A. If both the assertion and reason are true and reason is the correct explanation of the assertion.B. If both the assertion and reason are true but the reason is not correct explanation of the assertion.C. If the assertion is true but the reason is falseD. If the both the assertion and reason are false. |
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Answer» Correct Answer - C When water leaves the body through perspiration energy content of molecules remained in body, decreases, therefore temperature also decrease. Thus, perspiration form human body helps in cooling the body. |
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| 182. |
`gamma_(A)` of liquid is `7//8` of `gamma_(R)` of liquid. `alpha_(g)` is vessel isA. `(gamma_(R))/(8)`B. `(gamma_(R))/(12)`C. `(gamma_(R))/(24)`D. `(gamma_(R))/(36)` |
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Answer» Correct Answer - C `gamma_(A) = (7)/(8)gammaR` and `gamma_(A) = gamma_(R) - 3alpha` |
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| 183. |
The coefficient of linear exopansion of a metal is `1 xx 10^(-5//0)C`. The percentage increase in area of a square plate of that metal when it is heated through `100^(0)C` isA. `0.02%`B. `0.1%`C. `0.001%`D. `0.2%` |
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Answer» Correct Answer - D `beta = 2alpha, (DeltaA)/(A) 100 = betaDeltat100` |
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| 184. |
A metal plate of area `1.2 m^(2)` increases its area by `2.4 xx 10^(-4) m^(2)` when it is heated from `0^(@)C` to `100^(@) C`. The coefficient of cubical excpansion of the metal expressed in per `.^(@)C` isA. `2 xx 10^(-6)`B. `4 xx 10^(-6)`C. `6 xx 10^(-6)`D. `3 xx 10^(-6)` |
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Answer» Correct Answer - D `beta = (A_(2) - A_(1))/(A_(1) (t_(2) - t_(1)), gamma) = (3)/(2)beta` |
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| 185. |
Match the following |
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Answer» Correct Answer - A::B::C::D |
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| 186. |
Match the following |
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Answer» Correct Answer - A::B::C::D |
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| 187. |
Match the following |
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Answer» Correct Answer - A::B::C::D |
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| 188. |
Match the following |
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Answer» Correct Answer - A::B::C::D |
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| 189. |
A solid ball of metal has a spherical cavity inside it. The ball is cooled. The volume of the cavity willA. decreaseB. increaseC. reamain sameD. have its shape changed |
| Answer» Correct Answer - A | |
| 190. |
Match the following |
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Answer» Correct Answer - A::B::C::D |
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| 191. |
A solid sphere of radius b=4cm has a cavity of radius a=2cm. The cavity is filled with steam at `100^(@)C`. The solid sphere is placed inside the ice at `0^(@)C`. Thermal conductivity of material of sphere is 0.5 W/m`.^(@)C`. If ther ate of flow of heat through the sphere radially is `x pi J//s` then find the value of x. |
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Answer» Correct Answer - 8 |
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| 192. |
A thin brass sheet at `10^(@)C` and a thin steel sheet at `20^(@)C` have the same surface area. The common temperature at which both would have the same area is (Coefficient of linear expansion for brass and steel are respectively, `19 xx 10^(-6//@)C` are `11 xx 10^(-6//@)C)`A. `[email protected]`B. `-2.75^(@)C`C. `2.75^(@)C`D. `3.75^(@)C` |
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Answer» Correct Answer - A `t=(beta_(1)t_(1)-beta_(2)t_(2))/(beta_(1)-beta_(2))` |
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| 193. |
A brass sheet is `25 cm` long and `8 cm` breath at `0^(@) C`. Its area at `100^(@)C` is `(alpha = 18 xx 10^(-6 // ^(@))C)`A. `207.2 cm^(2)`B. `200.72 cm^(2)`C. `272 cm^(2)`D. `2000.72 cm^(2)` |
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Answer» Correct Answer - B `A_(2) = A_(1)(1 + betaDeltat) beta = 2alpha` |
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| 194. |
A thin brass sheet at `10^(@)C` and a thin steel sheet at `20^(@)C` have the same surface area. The common temperature at which both would have the same area is (Coefficient of linear expansion for brass and steel are respectively, `19 xx 10^(-6//@)C` are `11 xx 10^(-6//@)C)`A. `[email protected]`B. `-2.75^(@)C`C. `2.75^(@)C`D. `3.75^(@)C` |
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Answer» Correct Answer - A `t=(beta_(1)t_(1)-beta_(2)t_(2))/(beta_(1)-beta_(2))` |
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| 195. |
A pendulum clock gives correct time at `20^(@)C` at a place where `g= 10m//s^(2)`. The pendulum consists of a light steel rod connected to a heavy ball. If it is taken to a different place where `g = 10.01m//s^(2)` at what temperature the pendulum gives correct time ( `alpha` of steel of `10^(-5//@)C`)A. `30^(@)C`B. `60^(@)C`C. `100^(@)C`D. `120^(@)C` |
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Answer» Correct Answer - D `(Deltal)/(l) = (Deltag)/(g) = alphaDeltat` |
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| 196. |
A cylindrical block of length 0.4 m and area of cross-section `0.04 m^2` is placed coaxially on a thin metal disc of mass 0.4 kg and of the same cross - section. The upper face of the cylinder is maintained at a constant temperature of 400 K and the initial temperature of the disc is 300K. if the thermal conductivity of the material of the cylinder is `10 "watt"// m.K ` and the specific heat of the material of the disc is `600J//kg.K`, how long will it take for the temperature of the disc to increase to 350 K? Assume for purpose of calculation the thermal conductivity of the disc to be very high and the system to be thermally insulated except for the upper face of the cylinder. |
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Answer» Correct Answer - 1663.2s |
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| 197. |
The air of the atmosphere becomes cool at higher altitudes due toA. decrease in densityB. variation in pressureC. expansion of the airD. height above the surface of the earth |
| Answer» Correct Answer - C | |
| 198. |
The reading of Centigrade thermometer coincides with that of Fahrenheit thermometer in a liquid. The temperature of the liquid isA. `-40^(@)C`B. `0^(@)C`C. `100^(@)C`D. `300^(@)C` |
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Answer» Correct Answer - A `((F - 32)/(180) = (C - 0)/(100))` |
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| 199. |
In question number 3, the thermal conductivity (in `W m^(-1) K^(-1)`) if air isA. `1/10`B. `1/12`C. `1/14`D. `9/130` |
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Answer» Correct Answer - C The temperature difference across the plate. `DeltaT_("plate") = ((dQ)/dt)xx (l_("plate"))/(K_("plate") xx A) = (65 xx 4 xx 10^(-3))/(1 xx 1.3) = 0.2 K` `:. DeltaT_("air") = 13 - 2DeltaT_("plate") = 12.6 K` `K_("air") = (((dQ)/(dt))xxl_("air"))/(ADeltaT_("air")) = (65 xx 18 xx 10^(-3))/(1.3 xx 12.6) = 1/14 W m^(-1) K^(-1)` |
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| 200. |
In the question number of `45`, the equivalent thermal conductivity of the compound bar isA. `(K_(1)K_(2))/(K_(1)+K_(2))`B. `(2K_(1)K_(2))/(K_(1)+K_(2))`C. `(K_(1))/(K_(1)+K_(2))`D. `(K_(2))/(K_(1)+K_(2))` |
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Answer» Correct Answer - B Let K be thermal conductivity of the temperature bar. Heat current through the compound bar of length `2L` is `H = (KA(T_(1) - T_(2)))/(2L)` At steady state, `H = H_(1) = H_(2)` `:. (KA(T_(1) - T_(2)))/(2L) = (K_(1)A(T_(1) - T_(0)))/(L) "…..."(ii)` Substituting the value of `T_(0)` Eq (i) in (ii), we get `(K(T_(1)-T_(2)))/(2)= K_(1)[T_(1) - ((K_(1)T_(1) + K_(2)T_(2))/((K_(1)+K_(2))))] = (K_(1)K_(2)(T_(1)-T_(2)))/((K_(1)+K_(2)))` `rArr = (2K_(1)K_(2))/(K_(1)+K_(2))` |
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