(a) Why aerated water bottles kept under water during summer?
(b) Which property of liquid is responsible for spherical shape of drop?
(c) Why is moist air lighter than dry air?
(d) Define aqueous tension.
(e) What are units of a and b which are van der Waals constants?
(a) To reduce temperature, so as to reduce pressure, otherwise bottle may burst.
(b) Surface Tension.
(c) Moist air has water vapours which lowers vapour density, so it is lighter.
(d) It is pressure of water vapours at given temperature.
(e) Unit of a is L2 mol-2, b is L mol-1.
Assertion (A): Gases do not liquefy above their critical temperature, even on applying high pressure.
Reason (R): Above critical temperature, the molecular speed is high and intermolecular attractions cannot hold the molecules together because they escape because of high speed.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Which of the following changes decrease the vapour pressure of water kept in a sealed vessel?
(a) Decreasing the quantity of water
(b) Adding salt to water
(c) Decreasing the volume of the vessel to one-half
(d) Decreasing the temperature of water
One of the assumptions of kinetic theory of gases states that "there is no force of attraction between the molecules of a gas."How far is this statement correct? Is it possible to liquefy an ideal gas? Explain.
The critical temperature (Tc) and critical pressure (Pc) of C02 are 30.98 °C and 73 atm respectively. Can C02(g) be liquefied at 32 °C and 80 atm pressure?
With regard to the gaseous state of matter which of the following statements are correct?
(a) Complete order of molecules (b) Complete disorder of molecules
(c) Random motion of molecules (d) Fixed position of molecules
One of the assumptions of kinetic theory of gases is that there is no force of attraction between the molecules of a gas.
State and explain the evidence that shows that the assumption is not applicable for real gases.
Assertion (A): At constant temperature, PV vs V plot for real gases is not a straight line.
Reason (R): At high pressure all gases have Z> 1 but at intermediate pressure most gases have Z < 1.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Two different gases ˜A' and ˜9' are filled in separate containers of equal capacity under the same conditions of temperature and pressure. On increasing the pressure slightly, the gas ˜A' liquefies but gas ˜B' does not liquefy even on applying high pressure until it is cooled. Explain this phenomenon.
Explain the effect of increasing the temperature of a liquid on intermolecular forces operating between its particles. What will happen to the viscosity of a liquid if its temperature is increased?
Match the graph between the following variables with their names.
| Column I (Graphs) | Column II (Names) |
| (i) Pressure vs temperature graph at constant molar volume. | (a) Isotherms |
| (ii) Pressure vs volume graph at constant temperature. | (b) Constant temperature curve |
| (iii) Volume vs temperature graph at constant pressure. | (c) Isochores |
| (d) Isobars |
Assertion (A): Three states of matter are the result of balance between intermolecular forces and thermal energy of the molecules. .
Reason (R): Intermolecular forces tend to keep the molecules together but thermal energy of molecules tends to keep them apart.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
How much time would it take to distribute one Avogadro number of wheat grains if 1010 grains are distributed each second ?
Critical temperature for Co2 and CH4 are 31.1 °C and -81.9 °C respectively. Which of these has stronger intermolecular forces and why ?
Viscosity of a liquid arises due to strong intermolecular forces existing between the molecules. Stronger the intermolecular forces, greater is the viscosity. Name the intermolecular forces existing in the following liquids and arrange them in the increasing order of their viscosities. Also give reason for the assigned order in one line.Water, Hexane (CH3CH2CH2CH2CH2CH3), Glycerine (CH2OHCH(OH)CH2OH)
A weather balloon has a volume of 175 dm3 when filled with hydrogen gas at a pressure of 1.0 bar. Calculate the volume of the balloon when it rises to a height where the atmospheric pressure is 0.8 bar. Assume that temperature is constant.
Give an expression for the van der Wools equation. Give the significance of the constants used in the equation. What are their units?
(a) Why aerated water bottles kept under water during summer?
(b) Which property of liquid is responsible for spherical shape of drop?
(c) Why is moist air lighter than dry air?
(d) Define aqueous tension.
(e) What are units of a and b which are van der Waals constants?
The magnitude of surface tension of liquid depends on the attractive forces between the molecules. Arrange the following in increasing order of surface tension:
water, alcohol (C2H5OH) and hexane [CH3(CH2)4CH3)].
Assertion (A): The temperature at which vapour pressure of a liquid is equal to the external pressure is called boiling temperature.
Reason (R): At high altitude atmospheric pressure is high.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Pressure of l g of an ideal gas A at 27 °C is found to be 2 bar. When 2 g of another ideal gas B is introduced in the same flask at same temperature, the pressure becomes 3 bar. Find the relationship between their molecular masses.
Calculate the temperature of 4.0 moles of a gas occupying 5 dm3 at 3.32 bar (R = 0.083 bar dm3 K-1 mol-1)
Pay load is defined as the difference between the mass of the displaced air and the mass of the balloon. Calculate the pay load when a balloon of radius 10 m, mass 100 kg is filled with helium at 1.66 bar at 27 °C (Density of air = 1.2 kg m-3 and R = 0.083 bar dm3 K-1 mol-1).
At 25 °C and 760 mm ofHg pressure a gas occupies 600 mL volume. What will be its pressure at a height where temperature is 10 °C and volume of the gas is 640 mL?
State and explain Dalton’s law of partial pressures. Can we apply Dalton's law of partial pressures to a mixture of carbon monoxide and oxygen?
The pressure of a 1:4 mixture of dihydrogen and dioxygen enclosed in a vessel is one atmosphere. What would be the partial pressure of dioxygen?
(a) 0.8 x 105atm
(b) 0.008 Nm-2
(c) 8 x 104 Nm -2
(d) 0.25 atm
Value of universal gas constant (R) is same for all gases. What is its physical significance?
Name the energy which arises due to motion of atoms or molecules in a body. How is this energy affected when the temperature is increased?
Isotherms of carbon dioxide at various temperatures are represented in the following figure. Answer the following questions based on this figure.
(i) In which state will C02 exist between the points a and b at temperature T1
(ii) At what point will Co2 start liquefying when temperature is T1?
(iii) At what point will C02 be completely liquefied when temperature is T2?
(iv) Will condensation take place when the temperature is T3
(v) What portion of the isotherm at T1 represent liquid and gaseous C02 at equilibrium?
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30 °C?
Using the equation of state PV = nRT, show that at a given temperature, density of a gas is proportional to the gas pressure P.
How is compressibility factor expressed in terms of molar volume of the real gas and that of the ideal gas?
A flask was heated from 27 °C to 227 °C at constant pressure. Calculate the volume of the flask if 0.1 dm3 of air measured at 227 °C was expelled from the flask.
(a) What do you mean by’Surface Tension'of a liquid?
(b) Explain the factors which can affect the surface tension of a liquid.
An O2 cylinder has 10 LO2 at 200 atm. If patient takes 0.50 ml of O2 at 1 atm in one breath 37 °C, how many breaths are possible?
Under which of the following two conditions applied together, a gas deviates most from the ideal behaviour?
(a) Low pressure (b) High pressure
(c) Low temperature (d) High temperature
The variation of pressure with volume of the gas at different temperatures can be graphically represented as shown in figure.
On the basis of this graph answer the following questions.
(i) How will the volume of a gas change if its pressure is increased at constant temperature?
(ii) At a constant pressure, how will the volume of a gas change if the temperature is increased from 200 K to 400 K?
Assertion (A): At critical temperature liquid passes into gaseous state imperceptibly and continuously.
Reason (R): The density of liqtiid and gaseous phase is equal to critical temperature.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
