Which of the following has maximum thermal conductivity? (A) Iron (B) Coal (C) Nitrogen

Which of the following has maximum thermal conductivity?
(A) Iron
(B) Coal
(C) Nitrogen
by

1 Answer

Answer :

(A) Iron
by

Related questions

Which °fine metals has the maximum thermal conductivity? (1) Iron (2) Aluminium (3) Silver (4) Copper

Description : Which °fine metals has the maximum thermal conductivity? (1) Iron (2) Aluminium (3) Silver (4) Copper

Last Answer : (3) Silver Explanation: Silver has the best thermal conductivity of 429 W/mK at RT (295K). It is followed by copper, gold and aluminium. Metals generally have very good electrical conductivity, that leads to high thermal conductivity.

Which of the metals has the maximum thermal conductivity? (1) Iron (2) Aluminium (3) Silver (4) Copper

Description : Which of the metals has the maximum thermal conductivity? (1) Iron (2) Aluminium (3) Silver (4) Copper

Last Answer : Silver

Which of the following has the minimum thermal conductivity? (A) Nitrogen (B) Steel (C) Carbon black

Description : Which of the following has the minimum thermal conductivity? (A) Nitrogen (B) Steel (C) Carbon black

Last Answer : (A) Nitrogen

Which of the following has maximum thermal conductivity at the same temperature? (A) Steel (B) Petrol (C) Air (D) All have the same conductivity

Description : Which of the following has maximum thermal conductivity at the same temperature? (A) Steel (B) Petrol (C) Air (D) All have the same conductivity

Last Answer : (A) Steel

One face of a furnace wall is at 1030°C and the other face is exposed to room temperature (30°C). If the thermal conductivity of furnace wall is 3 W. m-1. k-1 and the wall thickness is 0.3 m, the maximum heat loss (in W/m) is (A) 100 (B) 900 (C) 9000 (D) 10000

Description : One face of a furnace wall is at 1030°C and the other face is exposed to room temperature (30°C). If the thermal conductivity of furnace wall is 3 W. m-1. k-1 and the wall thickness is 0.3 m, the maximum heat loss (in W/m) is (A) 100 (B) 900 (C) 9000 (D) 10000

Last Answer : (D) 10000

Power consumption during turbulent flow in agitation tank is proportional to the __________ of the liquid. (A) Viscosity (B) Thermal conductivity(C) Surface tension(D) Density

Description : Power consumption during turbulent flow in agitation tank is proportional to the __________ of the liquid. (A) Viscosity (B) Thermal conductivity (C) Surface tension (D) Density

Last Answer : (D) Density

Copper has very low (A) Malleability (B) Ductility (C) Tensile strength (D) Thermal & electrical conductivity

Description : Copper has very low (A) Malleability (B) Ductility (C) Tensile strength (D) Thermal & electrical conductivity

Last Answer : (C) Tensile strength

Coke oven regenerators are made of __________ bricks. (A) Fire clay (B) Silica (C) Low thermal conductivity (D) High electrical conductivity

Description : Coke oven regenerators are made of __________ bricks. (A) Fire clay (B) Silica (C) Low thermal conductivity (D) High electrical conductivity

Last Answer : (A) Fire clay

A bearing metal should not have (A) Enough plasticity (B) Low thermal conductivity (C) Low co-efficient of friction (D) High toughness

Description : A bearing metal should not have (A) Enough plasticity (B) Low thermal conductivity (C) Low co-efficient of friction (D) High toughness

Last Answer : (B) Low thermal conductivity

Coke oven walls are lined with __________ bricks. (A) Silica (B) Tar-dolomite (C) Low thermal conductivity (D) Fire clay

Description : Coke oven walls are lined with __________ bricks. (A) Silica (B) Tar-dolomite (C) Low thermal conductivity (D) Fire clay

Last Answer : (A) Silica

Brass tubes are used in the manufacture of tubes of evaporators used in sugar and salt industries, mainly because of its (A) High co-efficient of thermal expansion (B) Low thermal conductivity (C) High corrosion resistance (D) All (A), (B) and (C)

Description : Brass tubes are used in the manufacture of tubes of evaporators used in sugar and salt industries, mainly because of its (A) High co-efficient of thermal expansion (B) Low thermal conductivity (C) High corrosion resistance (D) All (A), (B) and (C)

Last Answer : (C) High corrosion resistance

Tin base and lead base alloys are used for bearing materials. Tin compared to lead has lower (A) Price (B) Corrosion resistance (C) Thermal conductivity (D) Abundant availability

Description : Tin base and lead base alloys are used for bearing materials. Tin compared to lead has lower (A) Price (B) Corrosion resistance (C) Thermal conductivity (D) Abundant availability

Last Answer : (D) Abundant availability

Pick out the wrong statement. (A) Pure rubber is as useless as pure gold as a material of construction (B) Thermal conductivity of aluminium is higher than that of copper; henceit is increasingly used for utensil making(C) Copper has poor weldability(D) Reinforced plastics are made from both thermoplastic as well asthermosetting plastics

Description : Pick out the wrong statement. (A) Pure rubber is as useless as pure gold as a material of construction (B) Thermal conductivity of aluminium is higher than that of copper; henceit is ... has poor weldability (D) Reinforced plastics are made from both thermoplastic as well as thermosetting plastics

Last Answer : (B) Thermal conductivity of aluminium is higher than that of copper; henceit is increasingly used for utensil making

Psychrometry deals with the properties of gas-vapor mixture. Humidity can be determined by the measurement of the __________ of a fibre. (A) Electrical resistance (B) Thermal conductivity (C) Strength (D) None of these

Description : Psychrometry deals with the properties of gas-vapor mixture. Humidity can be determined by the measurement of the __________ of a fibre. (A) Electrical resistance (B) Thermal conductivity (C) Strength (D) None of these

Last Answer : (A) Electrical resistance

With increase in temperature, the rate of leaching increases, because the (A) Diffusivity of solute increases (B) Viscosity of solvent decreases (C) Thermal conductivity of solute increases (D) None of these

Description : With increase in temperature, the rate of leaching increases, because the (A) Diffusivity of solute increases (B) Viscosity of solvent decreases (C) Thermal conductivity of solute increases (D) None of these

Last Answer : (A) Diffusivity of solute increases

If the thermal conductivity of a wall material is independent of temperature, the steady state temperature distribution in the very large thin plane wall having steady, uniform surface temperature follows __________ law. (A) Hyperbolic (B) Parabolic (C) Linear (D) Logarithmic

Description : If the thermal conductivity of a wall material is independent of temperature, the steady state temperature distribution in the very large thin plane wall having steady, uniform surface temperature follows __________ ... (A) Hyperbolic (B) Parabolic (C) Linear (D) Logarithmic

Last Answer : (C) Linear

The type of liquor circulation system to be ' employed in evaporators (viz. natural or forced circulation) is determined mainly by the __________ of the liquid. (A) Viscosity (B) Density (C) Thermal conductivity (D) Corrosive nature

Description : The type of liquor circulation system to be ' employed in evaporators (viz. natural or forced circulation) is determined mainly by the __________ of the liquid. (A) Viscosity (B) Density (C) Thermal conductivity (D) Corrosive nature

Last Answer : (A) Viscosity

__________ equation relates the thermal conductivity of a solid to its temperature. (A) Antoine (B) Kopp's (C) Lee's (D) Kistyakowsky

Description : __________ equation relates the thermal conductivity of a solid to its temperature. (A) Antoine (B) Kopp's (C) Lee's (D) Kistyakowsky

Last Answer : (C) Lee's

Which of the following has the highest thermal conductivity? (A) Brick (B) Air (C) Water (D) Silver

Description : Which of the following has the highest thermal conductivity? (A) Brick (B) Air (C) Water (D) Silver

Last Answer : (D) Silver

With increase in temperature, the thermal conductivity of steel (A) Increases (B) Decreases (C) Remains unchanged (D) Increases exponentially

Description : With increase in temperature, the thermal conductivity of steel (A) Increases (B) Decreases (C) Remains unchanged (D) Increases exponentially

Last Answer : (B) Decreases

For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally (A) Decreases (B) Increases (C) Remains unchanged (D) Increases exponentially

Description : For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally (A) Decreases (B) Increases (C) Remains unchanged (D) Increases exponentially

Last Answer : (A) Decreases

With increase in porosity, the thermal conductivity of a solid substance (A) Increases (B) Decreases (C) Remains unchanged (D) May increase or decrease; depends on the solid

Description : With increase in porosity, the thermal conductivity of a solid substance (A) Increases (B) Decreases (C) Remains unchanged (D) May increase or decrease; depends on the solid

Last Answer : (B) Decreases

Dittus-Boelter equation cannot be used for molten metals mainly due to its very low (A) Prandtl number (B) Grashoff number (C) Thermal conductivity (D) Viscosity

Description : Dittus-Boelter equation cannot be used for molten metals mainly due to its very low (A) Prandtl number (B) Grashoff number (C) Thermal conductivity (D) Viscosity

Last Answer : (A) Prandtl number

The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K = 0.04 W/m.°K and thickness 0.16m is 10 W/m2 . The temperature of the inside wall is - 5°C. The outside wall temperature is (A) 25°C (B) 30°C (C) 35°C (D) 40°C

Description : The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K = 0.04 W/m.°K and thickness 0.16m is 10 W/m2 . The temperature of the inside wall is - 5°C. The outside wall temperature is (A) 25°C (B) 30°C (C) 35°C (D) 40°C

Last Answer : (C) 35°C

Pick out the wrong statement. (A) Reciprocal of the resistance to heat flow is called thermal conductance (B) Unit of thermal conductance is W/°K (C) Thermal conductance of a wall of thickness 'L', thermal conductivity 'k' and heat flow area 'A' is kL/A (D) None of these

Description : Pick out the wrong statement. (A) Reciprocal of the resistance to heat flow is called thermal conductance (B) Unit of thermal conductance is W/°K (C) Thermal conductance of a wall of thickness 'L', thermal conductivity 'k' and heat flow area 'A' is kL/A (D) None of these

Last Answer : (C) Thermal conductance of a wall of thickness 'L', thermal conductivity 'k' and heat flow area 'A' is kL/A

Thermal conductivity of a conducting solid material depends upon its (A) Temperature (B) Porosity (C) Both (A) & (B) (D) Neither (A) nor (B)

Description : Thermal conductivity of a conducting solid material depends upon its (A) Temperature (B) Porosity (C) Both (A) & (B) (D) Neither (A) nor (B)

Last Answer : (C) Both (A) & (B)

Among liquids, water has a comparatively high value of thermal conductivity, due to its (A) Low density (B) High viscosity (C) Partial ionisation (D) Dense structure

Description : Among liquids, water has a comparatively high value of thermal conductivity, due to its (A) Low density (B) High viscosity (C) Partial ionisation (D) Dense structure

Last Answer : (C) Partial ionisation

Heat transfer occurs by natural convection because change in temperature causes difference in (A) Viscosity (B) Density (C) Thermal conductivity (D) Heat capacity

Description : Heat transfer occurs by natural convection because change in temperature causes difference in (A) Viscosity (B) Density (C) Thermal conductivity (D) Heat capacity

Last Answer : (B) Density

What is the thermal conductivity of a perfect heat insulator? (A) Zero (B) One (C) ∞ (D) Between 0 and ∞

Description : What is the thermal conductivity of a perfect heat insulator? (A) Zero (B) One (C) ∞ (D) Between 0 and ∞

Last Answer : (A) Zero

A metal wire of 0.01 m dia and thermal conductivity 200 W/m.K is exposed to a fluid stream with a convective heat transfer coefficient of 100 W/m2 .K. The Biot number is (A) 5.6 (B) 0.025 (C) 3.5 (D) 0.0035

Description : A metal wire of 0.01 m dia and thermal conductivity 200 W/m.K is exposed to a fluid stream with a convective heat transfer coefficient of 100 W/m2 .K. The Biot number is (A) 5.6 (B) 0.025 (C) 3.5 (D) 0.0035

Last Answer : (B) 0.025

The critical radius of insulation for a spherical shell is (where, K = thermal conductivity of insulating material h0 = heat transfer coefficient at the outer surface) (A) K/h0 (B) 2K/h0 (C) h0 /K (D) h0 /2K

Description : The critical radius of insulation for a spherical shell is (where, K = thermal conductivity of insulating material h0 = heat transfer coefficient at the outer surface) (A) K/h0 (B) 2K/h0 (C) h0 /K (D) h0 /2K

Last Answer : (B) 2K/h0

Low thermal conductivity of heat insulating materials is due to its (A) Dense structure (B) High proportion of air space (C) High specific heat (D) None of these

Description : Low thermal conductivity of heat insulating materials is due to its (A) Dense structure (B) High proportion of air space (C) High specific heat (D) None of these

Last Answer : (B) High proportion of air space

The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K0 + at, where, K is the thermal conductivity and T is the temperature (in °K). The units of 'a' in SI system will be (A) W/m.k (B) W/m (C) W/m.k

Description : The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K0 + at, where, K is the thermal conductivity and T is the temperature (in °K). The units of 'a' in SI system will be (A) W/m.k (B) W/m (C) W/m.k

Last Answer : (C) W/m.k

Heat transfer rate per unit area is called (A) Thermal conductivity (B) Heat flux (C) Heat transfer co-efficient (D) Thermal diffusivity

Description : Heat transfer rate per unit area is called (A) Thermal conductivity (B) Heat flux (C) Heat transfer co-efficient (D) Thermal diffusivity

Last Answer : (B) Heat flux

With increase in temperature, the thermal conductivity of non-metallic amorphous solids (A) Decreases (B) Increases (C) Remain constant (D) First decreases upto certain temperature and then increases

Description : With increase in temperature, the thermal conductivity of non-metallic amorphous solids (A) Decreases (B) Increases (C) Remain constant (D) First decreases upto certain temperature and then increases

Last Answer : (B) Increases

A composite flat wall of a furnace is made of two materials 'A' and 'B'. The thermal conductivity of 'A' is twice of that of material 'B', while the thickness of layer of 'A' is half that of B. If the temperature at the two sides of the wall are 400 and 1200°K, then the temperature drop (in °K) across the layer of material 'A' is (A) 125 (B) 133 (C) 150 (D) 160

Description : A composite flat wall of a furnace is made of two materials 'A' and 'B'. The thermal conductivity of 'A' is twice of that of material 'B', while the thickness of layer of 'A' is half that of B. If the temperature ... drop (in °K) across the layer of material 'A' is (A) 125 (B) 133 (C) 150 (D) 160

Last Answer : (D) 160

The left face of a one dimensional slab of thickness 0.2 m is maintained at 80°C and the right face is exposed to air at 30°C. The thermal conductivity of the slab is 1.2 W/m.K and the heat transfer co-efficient from the right face is 10 W/m2 .K. At steady state, the temperature of the right face in °C is (A) 77.2 (B) 71.2 (C) 63.8 (D) 48.7

Description : The left face of a one dimensional slab of thickness 0.2 m is maintained at 80°C and the right face is exposed to air at 30°C. The thermal conductivity of the slab is 1.2 W/m.K and the heat transfer co-efficient from the ... temperature of the right face in °C is (A) 77.2 (B) 71.2 (C) 63.8 (D) 48.7

Last Answer : (D) 48.7

A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of material A is twice that of B. Under the equilibrium, the temperature difference across the wall is 36°C. The temperature difference across the layer A is __________ °C. (A) 6 (B) 12 (C) 18 (D) 24

Description : A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of material A is twice that of B. Under the equilibrium, the temperature ... difference across the layer A is __________ °C. (A) 6 (B) 12 (C) 18 (D) 24

Last Answer : (B) 12

With increase in temperature, the thermal conductivity of fresh lubricating oil (A) Increases (B) Decreases (C) Remains unchanged (D) May increase or decrease; depends on its composition

Description : With increase in temperature, the thermal conductivity of fresh lubricating oil (A) Increases (B) Decreases (C) Remains unchanged (D) May increase or decrease; depends on its composition

Last Answer : (B) Decreases

Heat transfer rate described by Fourier's law will decrease, if the __________ increases. (A) Thermal conductivity (B) Thickness (C) Temperature difference (D) Heat transfer area

Description : Heat transfer rate described by Fourier's law will decrease, if the __________ increases. (A) Thermal conductivity (B) Thickness (C) Temperature difference (D) Heat transfer area

Last Answer : (B) Thickness

In SI units, thermal conductivity is expressed in (A) Watt/m.°K (B) Watt/m2 . °K (C) Watt/m2 . °K (D) Watt/m4 . °K

Description : In SI units, thermal conductivity is expressed in (A) Watt/m.°K (B) Watt/m2 . °K (C) Watt/m2 . °K (D) Watt/m4 . °K

Last Answer : (A) Watt/m.°K

What is the unit of thermal conductivity? (A) Kcal/hr. m2 °C (B) Kcal/hr.m.°C (C) Kcal/hr.m (D) Kcal/hr. °C

Description : What is the unit of thermal conductivity? (A) Kcal/hr. m2 °C (B) Kcal/hr.m.°C (C) Kcal/hr.m (D) Kcal/hr. °C

Last Answer : (B) Kcal/hr.m.°C

Thermal diffusivity of a material (A) Has the unit m2 /sec (B) Is defined as K/ρ . Cp (C) Is the ratio of thermal conductivity to thermal capacity (D) All (A), (B) and (C)

Description : Thermal diffusivity of a material (A) Has the unit m2 /sec (B) Is defined as K/ρ . Cp (C) Is the ratio of thermal conductivity to thermal capacity (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Finned tube heat exchangers (A) Give larger area per tube (B) Use metal fins of low thermal conductivity (C) Facilitate very large temperature drop through tube wall (D) Are used for smaller heat load

Description : Finned tube heat exchangers (A) Give larger area per tube (B) Use metal fins of low thermal conductivity (C) Facilitate very large temperature drop through tube wall (D) Are used for smaller heat load

Last Answer : (A) Give larger area per tube

Boiling point of a solution according to Duhring's rule is a linear function of the __________ of water. (A) Boiling point (at the same pressure) (B) Viscosity (C) Density (D) Thermal conductivity

Description : Boiling point of a solution according to Duhring's rule is a linear function of the __________ of water. (A) Boiling point (at the same pressure) (B) Viscosity (C) Density (D) Thermal conductivity

Last Answer : (A) Boiling point (at the same pressure)

Pick out the wrong statement. (A) Bubble size increases with the dynamic viscosity of the liquid in case of nucleate pool boiling (B) Thermal conductivity of a dry material is more than that of the damp material (C) Ratio of its capacity to economy equals the steam consumption in kg/hr in an evaporator (D) Vaporisation of organic substances in evaporator mostly causes foam formation

Description : Pick out the wrong statement. (A) Bubble size increases with the dynamic viscosity of the liquid in case of nucleate pool boiling (B) Thermal conductivity of a dry material is more than ... in kg/hr in an evaporator (D) Vaporisation of organic substances in evaporator mostly causes foam formation

Last Answer : (B) Thermal conductivity of a dry material is more than that of the damp material

In Fourier's law, the proportionality constant is called the (A) Heat transfer co-efficient (B) Thermal diffusivity (C) Thermal conductivity (D) Stefan-Boltzmann constant

Description : In Fourier's law, the proportionality constant is called the (A) Heat transfer co-efficient (B) Thermal diffusivity (C) Thermal conductivity (D) Stefan-Boltzmann constant

Last Answer : (C) Thermal conductivity

With increase in temperature, the thermal conductivity of most liquids (A) Increases (B) Decreases (C) Remain same (D) First increases upto a certain temperature and then becomes constant

Description : With increase in temperature, the thermal conductivity of most liquids (A) Increases (B) Decreases (C) Remain same (D) First increases upto a certain temperature and then becomes constant

Last Answer : (C) Remain same

Conductance is given by (where, x = thickness, A = heat flow area, K = thermal conductivity.) (A) x/KA (B) KA/x (C) K/Ax (D) A/Kx

Description : Conductance is given by (where, x = thickness, A = heat flow area, K = thermal conductivity.) (A) x/KA (B) KA/x (C) K/Ax (D) A/Kx

Last Answer : (B) KA/x

With increase in temperature, the thermal conductivity of a gas (A) Increases (B) Decreases (C) Remain same (D) May increase or decrease depending on the type of gas

Description : With increase in temperature, the thermal conductivity of a gas (A) Increases (B) Decreases (C) Remain same (D) May increase or decrease depending on the type of gas

Last Answer : (A) Increases