70 oC is above the critical temperature of CO2. Once CO2 is isothermally compressed at this temperature it would not liquefy irrespective of how high the pressure is but at very high pressures CO2 will not behave as an ideal gas.

At -65 oC under 10 atm pressure CO2 is in the solid phase. At room temperature (27 oC) under 10 atm pressure CO2 is in the vapour phase. At 10 atm pressure, CO2 can exist in all three phases depending upon the temperature. Therefore as CO2 is heated from -65 oC to room temperature at a constant pressure of 10 atm it goes from the solid phase to liquid phase and then ultimately it goes into the...

At room temperature (27 oC) and 4 atm pressure CO2 exits in the vapour phase. The pressure 4 atm is less than the pressure at the triple point and therefore points corresponding to all temperatures and this pressure lie in the solid and vapour region. Once we start compressing CO2 from room temperature at this constant pressure CO2 turns from vapour to solid directly without going through the...

The temperature -60 oC lies to the left of the triple point of water i.e. in the region of solid and vapour phases. Once we start compressing CO2 at this temperature starting from 1 atm pressure it will directly convert into solid without going through the liquid phase.

CO2 is liquid at 15 oC under 56 atm pressure as the point corresponding to this condition lies in the liquid region in the given P-T phase diagram of carbon dioxide.

CO2 is solid at -60 oC under 10 atm pressure as the point corresponding to this condition lies in the solid region in the given P-T phase diagram of carbon dioxide.

CO2 is vapour at -70 oC under 1 atm pressure as the point corresponding to this condition lies in vapour region in the given P-T phase diagram of carbon dioxide.

The critical temperature and pressure for CO2 are 31.1 oC and 73.0 atm respectively. If the temperature exceeds this critical value of temperature CO2 would not liquefy no matter how high the pressure is.

Both fusion and boiling point of CO2 decrease with decrease in pressure. This we can see from the solid lines in the P-T phase diagram of CO2.

At the triple point temperature of -56.6 oC and pressure 5.11 atm the solid, liquid and vapour phases of co-exist in equilibrium.

Let a body initially be at temperature T1
Let its final Temperature be T2
Let the surrounding temperature be T0
Let the temperature change in time t.
According to Newton's Law of cooling
where K is a constant.
We have been given that the body cools from 80 oC to 50 oC in 5 minutes when the surrounding temperature is 20 oC.
T2 = 50 oC
T1 = 80 oC
T0 = 20 oC
t = 5 min = 300 s.
For T1 = 60 oC...

Heating systems based on the circulation of steam are more efficient in warming a building than those based on the circulation of hot water because the same amount of steam at 100 oC contains more energy available for heat dissipation than the same amount of water at 100 oC in the form of latent heat of vaporization.

The sun rays contain infrared radiations. These are reflected back by the lower part of the atmosphere after being reflected by the surface of the earth and are trapped inside the atmosphere thus maintaining the Earth's temperature at a hospitable level. Without these rays being trapped the temperature of the earth will go down severely and thus the Earth without its atmosphere would be...

An optical pyrometer relates the brightness of a glowing body with its temperature. In the open because of other sources of light the sensor in the optical pyrometer does not detect the true brightness of a red hot piece of iron and thus does not predict its temperature correctly whereas in the furnace the piece of iron is the only source of light and the sensor detects its brightness correctly...

Brass is a good conductor of heat. Therefore once someone touches brass heat from their body flows into it and it feels cold, in case of a wooden tray, no such conduction of heat from the body takes place as wood is a very poor conductor of heat.

A body with a large reflectivity is a poor absorber. As we know a body which is a poor absorber will as well be a poor emitter. Therefore a body with large reflectivity is a poor emitter.

The rate at which water boils, R = 6.0 kg min-1
The heat of vaporisation of water,
The rate at which heat enters the boiler
The base area of the boiler, A = 0.15 m2
Thickness, l = 1.0 cm
Thermal conductivity of brass
The temperature inside the boiler = Boiling point of water = 100 oC
Let the temperature of the flame in contact with the boiler be T
Amount of heat flowing into the boiler...

Side of the box s = 30 cm
Area available for conduction A
A = 6s2
A=6(30)2
A=5400 cm2 = 0.54 m2
Temperature difference = 45 oC
Co-efficient of thermal conductivity of thermacole is k = 0.01 J s-1 m-1 K-1
Width of the box is d = 5 cm
Heat absorbed by the box in 6 hours is
Heat of fusion of water is
Amount of ice which has melted is m'
Amount of ice left after 6 hours = 4 - 0.313 = 3.687 kg

Initial Temperature of the boy = 101 oF
Final Temperature of the boy = 98 oF
Change in Temperature is
Mass of the child is m = 30 kg
Specific heat of human body = 1000 cal kg-1 oC-1
Heat released is
Latent heat of evaporation of water = 580 cal g-1
The amount of heat lost by the body of the boy has been absorbed by water.
Let the mass of water which has evaporated be m'
Time in which the...

Monoatomic gases have only translational degree of freedom but diatomic gases have rotational degrees of freedom as well. The temperature increases with increase in the spontaneity of motion in all degrees. Therefore to increase the temperature of diatomic gases more energy is required than that required to increase the temperature of monoatomic gases by the same value owing to higher degrees...

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