Topic: Thermal Properties of Matter (Test 2)



Topic: Thermal Properties of Matter
Q.1
If V is the initial volume, ΔV the fractional change in volume of a substance for temperature change ΔT, the coefficient of volume expansion, αV is defined as
A. αV=(ΔVV)1ΔT
B. αV=(2VV)1T
C. αV=(VV)12T
D. αV=(V2V)1T
Answer : Option A
Explaination / Solution:

increase in volume per unit original volume per Kelvin rise in temperature is called coefficient of volume expansion, 


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Q.2
Which of these materials has low coefficient of volume expansion αV ?
A. pyrex glass
B. paraffin
C. water
D. alcohol
Answer : Option A
Explaination / Solution:

Glass is a ceramic material made from silica.So that it has lower coefficient of volume expansion in comparison to metal and liquid.

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Q.3
Which of these materials have high coefficients of volume expansion ?
A. invar
B. Pyrex glass
C. alcohol
D. glass
Answer : Option C
Explaination / Solution:

Alcohal has higher coefficient of volume expansion in comparison to glass and Invar.

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Q.4
expansion of water is called anomalous because
A. it expands on cooling from 10 C to 4 C
B. it contracts on heating from 0 C to 4 C
C. it expands on heating from 0 C to 4 C
D. it contracts on cooling from 4 C to 0 C
Answer : Option B
Explaination / Solution:

Liquids expand on heating and contract on cooling at moderate temperatures. But water exhibits an exceptional behaviour. When it is heated from 0 ºC, it actually contracts rather than expanding, up to 4 ºC. The volume of water is minimum at 4 ºC. Beyond 4 ºC, water starts expanding.This behaviour of water between 0 ºC and 4 ºC is called anomalous expansion of water..

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Q.5
Animal and plant life in lakes and ponds are not destroyed because
A. freezing takes place at the bottom first
B. water contracts on cooling at all temperatures
C. water expands on heating at all temperatures
D. freezing takes place at the top first and bottom layers are not frozen as temperature in bottom layers is more than zero
Answer : Option D
Explaination / Solution:

As and when water is cooled down to its freezing point the thickness T of the ice layer increases. The increase in thickness of ice decreases the rate of cooling of water and thus freezing process slows down.

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Q.6
For an ideal gas the coefficient of volume expansion at constant pressure is
A. 1/2T; T is the temperature
B. 1/T; T is the temperature
C. 2/T; T is the temperature
D. 1/3T; T is the temperature
Answer : Option B
Explaination / Solution:

γ=ΔVVΔTPV=nRTV=nRTPPΔV=nRΔTΔV=nRΔTPγ=nRΔTPnRTP×1ΔT=nRΔTP×PnRT×1ΔT=1T
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Q.7
Thermal stress is stress induced in solids
A. due to vibration of molecules
B. if thermal expansion is allowed by floating it’s ends
C. due to dropping in cold water
D. if thermal expansion is prevented by fixing its ends rigidly
Answer : Option D
Explaination / Solution:

If temperature deformation is permitted to occur freely, no load or stress will beinduced in the structure. In some cases where temperature deformation is not permitted, an internal stress is created. The internal stress created is termed as thermal stress .

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Q.8
If m is the mass of a substance, ΔQ the energy required to raise the temperature by ΔT the specific heat is given by
A. s = mΔQ.
B. s = .
C. s =  / 
D. s=1mQΔT
Answer : Option D
Explaination / Solution:

The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius.

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Q.9
The latent heat of fusion is. 
A. the heat per unit mass required changing a substance from solid into liquid, at high temperature and low pressure
B. the heat per unit mass required changing a substance from solid into liquid, at high pressure and low temperature
C. the heat per unit mass required changing a substance from solid into liquid, at the same temperature and pressure
D. the heat per unit mass required changing a substance from liquid into solid, at the same temperature and pressure
Answer : Option C
Explaination / Solution:

The enthalpy of fusion of a substance, also known as (latent) heat of fusion, is the change in its enthalpy resulting from providing energy, typically heat, to a specific quantity of the substance to change its state from a solid to a liquid at constant pressure.

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Q.10
The latent heat of vaporization  is.
A. the heat per unit mass required to change a substance from vapor to the liquid state without change in the temperature and pressure
B. the heat per unit mass required to change a substance from liquid to the vapor state without change in the temperature and pressure
C. the heat per unit mass required to change a substance from liquid to the vapor state at high pressure and low temperature
D. the heat per unit mass required to change a substance from liquid to the vapor state , at high temperature and low pressure
Answer : Option B
Explaination / Solution:

Latent heat of vaporization is actually the total amount of enthalpy (a kind of energy/heat) necessary to accomplish a phase change for a liquid or gas at the boiling/condensation point. Phase changes are generally considered at constant pressure, rather than constant volume.

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