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Thermal properties of matter exhibit heat conductivity and determine the nature of the matter in presence of heat. Therefore, thermal properties are shown by objects when heat passes through them.
In thermal properties of matter, Molar specific heat [molar heat capacity (C)] is the same as above Specific Heat, with the only difference being that mass (m) of the substance is replaced by mole (n) of the substance. In the formula, n is the number of moles. The S.I unit for this is J mol-1 K-1.
Thermal Properties of Matter MCQs
Ques: ………….. Is the form of energy transferred between two systems or a system and its surroundings by virtue of temperature difference.
- Temperature
- Heat
- none
- Both a and b
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Ans: b-Heat
Explanation:
Consider the example of a glass of ice-cold water left outside on a table on a hot day. After some time the water will warm up. This means that the temperature of the surrounding medium and the ice-cold water are different, heat transfer takes place until the surrounding temperature and system temperature becomes the same. We can also say that heat is the form of energy transferred from one system to another or from system to surrounding by virtue of temperature difference.
Ques: On what scale the temperature is only positive?
- Kelvin
- Reaumur
- Celsius
- Fahrenheit
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Ans: a-Kelvin
Explanation:
The degree of hotness and coldness of the body is the measure of temperature. The SI unit of temperature is Kelvin (K). On the kelvin scale, the absolute zero temperature is 0 Kelvin (K). we cannot measure temperature below 0 K on kelvin scale. So temperature is only positive on kelvin scale.
Ques: The temperature………. during the melting of solid.
- Increases
- Decreases
- Does not change
- Depending on the nature of the solid, it may increase or decrease.
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Ans: c- Does not change
Explanation: Change of state of solid to liquid is called melting. Melting point is the temperature at which solid starts to turn into liquid. The expansion of solid takes place when temperature increases. During the change of state from solid to liquid, all the heat given to solid is used to change the state from solid to liquid. That's why the temperature of the material Does not change.
Ques: What is the relation between Fahrenheit and Celsius?
- C = 59(F-32)
- C = 95(F-32)
- C = 59(32-F)
- C = 95(32-F)
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Ans: a- C = 59(F-32)
Explanation:
On a celsius scale ice point is taken at 0° and steam point at 100°. The temperature measured on the scale of degree celsius (°C). On the other hand, the thermodynamic scale is also known as the kelvin scale. The temperature measured on this scale is in kelvin (K).
Celsius, Fahrenheit and Kelvin are related to each other by the following equation:
F-329 = C5 =K-2735
Therefore,
Relation between Celsius and Fahrenheit,
F-329 = C5
C= 59(F-32)
Ques: On Fahrenheit Scale what will be the value of 350K?
- 150°F
- 167°F
- 122°F
- 170.6°F
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Ans: d- 170.6°F
Explanation: Given, Temperature in Kelvin = 350K
Celsius, Fahrenheit and Kelvin are related to each other by the following equation:
F-329 = C5 =K-2735
Therefore,
Relation between Kelvin and Fahrenheit,
F-329 = K-2735
F-329 = 350-2735
F-329 = 15.4
F = (15.4 x 9)+32
F = 170.6 °F
Ques: Choose the least thermal conductivity from the following?
- Air
- Diamond
- Water
- Iron
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Ans: a- Air
Explanation: Thermal conductivity is the ability of the material to conduct heat. Thermal conductivity is one of the properties of the material and it changes from material to material. It is denoted by ‘K’ and its SI unit is (W/mK). Higher the thermal conductivity indicates the material is good heat conductor and lower the number represents poor heat conductor or insulator
Therefore, Kair< Kwater< Kiron< Kdiamond
Ques: In severe winters, the surface of the lake is frozen but the water below the surface is still in the liquid form. Why?
- Since the surface of the lake and air around is at the same temperature, no heat is lost.
- Ice is a bad conductor of heat
- None of the above
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Ans: b- ice is the bad conductor of heat
Explanation: Temperature of air changes faster than water. So, in winters air compared to water air cools down faster. As the surface of the water is in contact with air directly, it cools down quickly compared to water at the bottom of the lake. As the temperature falls the source freezes and turns to ice.
We know the density of water is more than that of ice. So, ice keeps floating on the surface and it gets thicker. Thick ice acts as an insulator between cold air and warm water at the bottom of the surface. Which results in water at the bottom staying liquid. Thus we can say that ice is a bad conductor of heat.
Ques: Charles Law is given by
- T = Constant
- V = Constant
- V/T = Constant
- None of the above
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Ans: c- V/T= Constant
Explanation: Charles Law is defined as the volume of the ideal gas is directly proportional to the absolute temperature at constant pressure. That is when pressure is held constant, the volume of quantity of gas is related to the temperature as V/T=Constant. So the option c is the correct answer.
Ques: For an Ideal gas Boyle’s law holds…..
- Adiabatic process c. Isochoric changes
- Isothermal changes d. Isobaric changes
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Ans: b-Isothermal changes
Explanation: Isothermal process is defined as the process in which a system goes into physical changes in which temperature remains constant. In Boyle's law, for ideal gas of given mass, volume of gas is inversely proportional to the pressure at constant temperature.
Therefore, V ∝ 1P or PV = Constant
Therefore, P1V1=P2V2
Therefore, for ideal gas Boyle’s law holds isothermal changes
Ques: 37°C = ……….°F
- -92°F
- 102°F
- c. 100.1°F
- d. 98.6°F
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Ans: d-98.6°F
Explanation:
Given, Temperature in Degree celsius = 37°C
Celsius, Fahrenheit and Kelvin are related to each other by the following equation:
F-329 = C5 =K-2735
Therefore,
Relation between Celsius and Fahrenheit,
F-329 = C5
F-329 = 375
F-329 = 7.4
F = (7.4 x 9)+32
F = 98.6 °F
Ques: At what temperature Celsius is equal to Fahrenheit?
- 40°
- -40°
- 273°
- -273°
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Ans: b-(-40°)
Explanation:
The measurement of the degree of hotness and coldness of the body is called temperature.
Celsius, Fahrenheit and Kelvin are related to each other by the following equation:
F-329 = C5 =K-2735
Therefore,
Relation between Celsius and Fahrenheit,
F-329 = C5
The temperature should be equal in fahrenheit and celsius
Let, F = C = x
Therefore,
x-329 = x5
x = 59(x-32)
9x = 5x - 160
4x = -160
x = -40°
Therefore, -40°C = -40°F
Ques: Solid is directly converted into gaseous state on heating, this process is called as……….
- Condensation
- Sublimation
- Evaporation
- Diffusion
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Ans: b- Sublimation
Explanation:
Sublimation is the process of conversion of solid directly to gaseous state. When the boiling point of a substance is less than the melting point of the substance, sublimation takes place. Heat of sublimation is the amount of heat required to convert a unit mass of solid into vapour at a given temperature.
Ques: During the phase change, heat given to the substance is called as……..
- Thermal capacity
- Latent heat
- Specific heat
- None of the above
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Ans: b- Latent heat
Explanation: During the phase change, heat given to the substance is called Latent heat. Depending on phase change it can be either latent heat of evaporation or latent heat of fusion. Latent heat of fusion is the amount of heat required to change state from solid to liquid. Latent heat of evaporation is the amount of heat required to change state from liquid to gaseous state.
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