CBSE Questions for Class 11 Engineering Physics Thermal Properties Of Matter Quiz 7 - MCQExams.com

A closed cubicle box made of perfectly insulating material has walls of thickness $$8$$ cm and the only way for heat to enter and leave the box is through the metal plugs $$A$$ and $$B$$ each of cross section $$12cm^2$$ and length $$8$$ cm fixed in the opposite walls of the box as shown in figure. Outer surface of $$A$$ is kept at $$100^oC$$ while outer surface of $$B$$ is at $$4^oC$$. The thermal conductivity of the material of the plugs is $$0.5cal/s/cm/\space^oC$$. A source of energy generating $$36$$cal/s is enclosed inside the box. The equillibrium temperature of the inner surface of the box (assuming that it is same at all points on the inner surface) is

147379_7a7f155e76d14c6bb1485dfc2018fee7.png
  • $$38^oC$$
  • $$57^oC$$
  • $$76^oC$$
  • $$85^oC$$
A sample of an ideal gas occupies a volume of 'V' at a pressure 'P' and absolute temperature 'T'. The mass of each molecule is 'm'. The equation for density is 
  • mkT
  • P/kT
  • P/(kTV)
  • Pm/kT
An electric heater kept in vacuum is heated continuously by passing an electric current. Its temperature
  • will go rising with the time.
  • will stop rising after sometime as it will lose heat to the surroundings by conduction.
  • will rise for sometime and thereafter will start falling.
  • will become constant after some time because of loss heat due to radiation.
A liquid used as a coolant in automobile engine is 
  • alcohol
  • engine oil
  • water
  • benzene
The air density at Mount Everest is less than that at the sea level. It is found by mountaineers that for one trip lasting a few hours, the extra oxygen needed by them corresponds to 30,000cc at sea level (pressure 1 atmosphere, temperature 27$$^o$$C). Assume that the temperature around Mount Everest is -$$73^o$$C and that the oxygen cylinder has a capacity of 5.2 litters. The pressure at which oxygen be filled (at site) in the cylinder is
  • 3.86 atm
  • 5.00 atm
  • 5.77 atm
  • 1 atm
On which one of the factors does the nature of the thermal radiation depend inside an enclosure?
  • size of the enclosure
  • temperature
  • nature of the walls
  • color of the walls
A vessel contains air at a temperature of $$15^{0}C$$ and 60% R.H. What will be the R.H if it is heated to $$20^{0}C$$? (S.V.P at $$15^{0}C$$ is 12.67 & at $$20^{0}C$$ is 17.36mm of Hg respectively)
  • 262%
  • 26.2%
  • 44.5%
  • 46.2%
Final volume of the system will be nearly -
  • $$6.2m^{3}$$
  • $$2.8m^{3}$$
  • $$4.5m^{3}$$
  • $$1.4m^{3}$$
A vessel has 6g of hydrogen at pressure P and temperature 500K. A small hole is made in it so that hydrogen leaks out. How much hydrogen leaks out if the final pressure is $$P/2$$ and temperature falls to 300K?
  • 2g
  • 3g
  • 4g
  • 1g
A graph is plotted with PV/T on y-axis and mass of the gas along x-axis for different gases. The graph is 
  • a straight line parallel to x-axis for all the gases
  • a straight line passing through origin with a slope having a constant value for all the gases
  • a straight line passing through origin with a slope having different values for different gases
  • a straight line parallel to y-axis for all the gases
If pressure of a gas contained in a closed vessel is increased by 0.4% when heated by $$1^{0}C$$, the initial temperature must be 
  • 250K
  • $$250^{0}C$$
  • 2500K
  • $$25^{0}C$$
An ideal gas is found to obey an additional law $$VP^{2}$$ = constant. The gas is initially at temperature T and volume V. When it expands to a volume 2V, the temperature becomes :
  • $$\displaystyle\ \frac{T}{\sqrt{2}}$$
  • $$2T$$
  • $$\displaystyle\ \frac{2T}{\sqrt{2}}$$
  • $$4T$$
The density of water at $$4^{\circ}C$$ is $$1000\:kg\:m^{-3}$$ and at $$104^{\circ}C$$ it is $$958.4\:kg\:m^{-3}$$. The cubic expansivity of water between these temperature is
  • $$4.16\times 10^{-5}(K)^{-1}$$
  • $$2.08\times 10^{-5}(^{\circ}C)^{-1}$$
  • $$4.16\times 10^{-4}(^{\circ}C)^{-1}$$
  • $$2.08\times 10^{-4}(K)^{-1}$$
Two containers A and B contain liquid at 50C. Two metal balls one at 50C and the other at 30C are dropped in the containers A and B respectively. In which container will the transfer of heat take place?
269430.jpg
  • $$B$$
  • $$A$$
  • $$A$$ & $$B$$
  • None of these
A glass of cold water whose particles had a low average kinetic energy was placed on a table. The average kinetic energy in the cold water increased, while the average kinetic energy of the part of the table under the glass decreased. What do you think happened?
  • Thermal energy was transferred from the table to the glass of cold water.
  • Thermal energy was transferred from the glass of cold water to the table.
  • Entropy was transferred from glass of water to table 
  • None of these.
In the diagram shown, will the convection current be clockwise or anticlockwise on the left part of the figure?
268379_edcd876dd6ec47ef8f0b9506232fa4f4.png
  • Anticlockwise
  • Clockwise
  • Will keep on changing
  • Can't be said
When the specific heat of a solid is measured  by the method of mixture, the heat is lost to surroundings from the calorimeter by the process of
  • radiation
  • conduction
  • convection
  • both conduction and convection
The amount of heat required to raise the temperature of 100g of copper (sp. heat = 390 J/kg$$^o$$ C) from $$40^o$$ to $$90^o$$ is
  • 1950 J
  • 2350 J
  • 2550 J
  • None of these
Thermal energy is always transferred from .............. to ............. temperatures
  • Lower, higher
  • Higher, lower
  • Both $$A$$ and $$B$$
  • Can't be determined
A ........... is a device used to measure heat
  • Calorimeter
  • Barometer
  • Lactometer
  • None of these
When you heat a bowl of water, we can observe that water starts circulating. This demonstrates:
  • conduction
  • convection
  • radiation
  • none
A gas behaves more closely like an ideal gas at
  • low pressure and low temperature
  • low pressure and high temperature
  • at all pressure and temperature
  • none of these
If T represents the absolute temperature of an ideal gas, the volume coefficient of thermal expansion at constant pressure is proportional to:
  • T
  • T$$^2$$
  • 1/T
  • 1/T$$^2$$
If two conducting slabs of thickness $$d_1$$ and $$d_2$$, and thermal conductivity $$K_1$$ and $$K_2$$ are placed together face to face as shown in figure in the steady state temperatures of outer surfaces are $$O_1$$, and $$O_2$$. The temperature of common surface is 
310979_3d8d49b71c2041158f3936cc254c79a0.png
  • $$\displaystyle{\frac{K_1O_1d_1 + K_2O_2d_2}{K_1d_1 + K_2d_2}}$$
  • $$\displaystyle{\frac{K_1O_1 + K_2O_2}{K_1 + K_2}}$$
  • $$\displaystyle{\frac{K_1O_1 + K_2O_2}{O_1 + O_2}}$$
  • $$\displaystyle{\frac{K_1O_1d_2 + K_2O_2d_1}{K_1d_1 + K_2d_2}}$$
Two models of a windowpane are made. In one model, two identical glass panes of thickness 3 mm are separated with an air gap of 3 mm. This composite system is fixed in the window of a room. The other model consists of a single glass pane of thickness 6 mm, the temperature difference being the same as for the first model. The ratio of the heat flow for the double pane  to that for the single pane is ($$K_{glass}\, =\, 2.5\, \times\, 10^{- 4}$$ cal / m. $$^{\circ}C$$ and $$K_{air}\, =\, 6.2\, \times\, 10^{- 6}$$ cal/s.m. $$^{\circ} C$$)
  • 1/20
  • 1/70
  • 31/1312
  • 31/656
Three copper rods and three steel rods each of length $$l$$ = 10 cm and area of cross - section $$1\, cm^2$$ are connected as shown If ends A and E are maintained at temperatures $$125^{\circ}$$C and $$o^{\circ}$$C respectively, calculate the amount of heat flowing per second from the hot to cold function. $$[K_{cu}\, =\, 400\, W/m-K,\, K_{steel}\, =\, 50\, W/m-K]$$
300833_fbeb2f312efa4cffaf9758fc7b34ec0c.png
  • 2 watt
  • 9 watt
  • 4 watt 
  • 10 watt
A manufacture marks the thermometer wrongly. At 0$$^o$$ C it reads -10$$^o$$ C, at 100$$^o$$ C it reads 85$$^o$$C. Then the reading at 50$$^o$$ C will be :
  • 40$$^o$$ C
  • 32.5$$^o$$ C
  • 37.5$$^o$$ C
  • 42.5$$^o$$ C
Two identical beakers with negligible thermal expansion are filled with water to the same level at $$^o$$C. If one say A is heated while the other B is cooled, then : 
  • water level in A must rise
  • water level in B must rise
  • water level in A must fall
  • water level in B must fall
Absolute zero corresponds to :
  • $$- 273 K$$
  • $$- 273^{\circ}C$$
  • $$273^{\circ} F$$
  • None of these
A brass boiler has a base area of $$0.15 m^2$$ and thickness 1.0 cm. It boils water at the rate of 6.0 kg/min when placed on a gas stove. The temperature (approximately) of the part of the flame in contact with the boiler is (Thermal conductivity of brass $$= 107.4Js^{-1}m^{-1} {\;} ^oC^{-1}$$, Heat of vaporization of water $$= 2256\times 10^3J kg^{-1})$$.
  • 2400 K
  • $$240^oC$$
  • $$2400^oC$$
  • $$24000^oC$$
Which of the following curve represent variation of density of water with temperature best :   
The volume of a perfect gas at NTP is
  • 22.4 litres
  • 2.24 litres
  • 100 litres
  • None of these
A thermometer uses 'density of water' as thermometric property. The actual reading in the thermometer is 'height of water' (h) which is inversely proportional to density of water (d). In a certain temperature range, density of water varies with temperature as shown. The graph is symmetric about the maximum
Two identical bodies ( of same mass and specific heat ) at different temperatures $$T_1\, and\, T_2$$ show the same reading of height $$h_1\, =\,h_2$$ the thermometer. The bodies are brought into contact and allowed to reach thermal equilibrium. The thermometer reading 'height of water for final equilibrium state $$h_1$$ satisfies.

335496_0a315c6370af4f689c5c8cd325bc4f68.png
  • $$h_f\, = \displaystyle \frac{h_1\, +\, h_2}{2}\, =\, h_1\, =\, h_2$$
  • $$h_f\, <\, h_1\, =\, h_2$$
  • $$h_f\, >\, h_1\, =\, h_2$$
  • $$h_f$$ may be greater or less than $$h_1\, =\, h_2$$, depending on the specif heat of the bodies
  • Information is not enough.
The boiling point of mercury is 367$$^o$$C. A mercury thermometer can be used to measure a temperature of 500$$^o$$C;
  • by filling the space above mercury with oxygen at high pressure
  • by filling the space above mercury with nitrogen at low pressure
  • by filling the space above mercury with nitrogen at high pressure
  • by keeping the space above mercury as vacuum
A quantity of air $$(\gamma = 1.4)$$ at 27$$^o$$C is compressed suddenly, the temperature of the air system will
  • fall
  • rise
  • remain unchanged
  • first rise and then fall
The temperature to which a gas must be cooled before it can't be liquefied by pressure alone is called its
  • Critical temperature
  • Saturation point
  • Boiling point
  • Freezing point
Which of the following  curve represent variation of  density of water with temperature best:
Real gases obey ideal gas laws more closely at:
  • low pressure and low temperature
  • low pressure and high temperature
  • high pressure and low temperature
  • high pressure and high temperature
A manufacture marks the thermometer wrongly.So At $$0^{\circ}C$$ it reads $$10^{\circ}C$$, at $$100^{\circ}C$$ it reads $$85^{\circ}C$$. Then the reading at $$50^{\circ}C$$ will be :
  • $$40^{\circ}C$$
  • $$32.5^{\circ}C$$
  • $$37.5^{\circ}C$$
  • $$42.5^{\circ}C$$
Two gases $$A$$ and $$B$$ having the same temperature $$T$$, same pressure $$P$$ and same volume $$V$$ are mixed. If the mixture is at the same volume $$V$$, the pressure of the mixture is
  • $$P$$
  • $${P}/{2}$$
  • $$2P$$
  • $$4P$$
A temperature of $$15^o$$ C on the Fahrenheit scale is ________________.
  • $$59^0$$ F
  • $$27^0$$ F
  • $$-27^0$$ F
  • $$-59^0$$ F
The volume of mole of a prefect gas at NTP is ______.
  • 22.4 litres
  • 2.24 litres
  • 100 litres
  • none of these
At 4$$ \displaystyle ^{\circ}C $$, the density of water is _____ $$ \displaystyle kg/m^{3} $$
  • 1000
  • 1
  • 200
  • 0.1
When an inflated tyre bursts, the air escaping out __________.
  • will get heated up
  • will be cooled
  • will not undergo any change in its temperature
  • will be liquefied
The S.I unit of heat is
  • Joule
  • Calorie
  • Newton
  • None of these
State whether true or false.
When water is heated from 0$$^oC$$, it continuously expands. 
  • True
  • False
Two blocks of steel A and B, A being two times heavier than B, are at 40$$^o$$C. The ratio of heat content of A to B is:
  • 1
  • 4
  • 2
  • $$\displaystyle \frac{1}{2}$$
Alcohol expands more than mercury. True/False
  • True
  • False
Alcohol thermometers can be used for finding high temperatures
  • True
  • False
The figure shows that the level of water in the round bottom flask was initially at A.  When heated the level fell to B and finally rises to C. Which of the following statements justify this observation

422834_86596eb4207e4870a6f911e4413e404a.bmp
  • That's how all liquids behave
  • Anomalous expansion of water
  • The dissolved gases come out decreasing the volume
  • None of these
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