Chemistry

States of Matter

Question:

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?

Answer:

C02 gas cannot be liquefied at 32 °C by applying a pressure of 80 atm. This is because the temperature is higher than critical temperature of C02.

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States of Matter

Q 1.

Define an ideal gas.

Q 2.

2.9 g of a gas at 95 °C occupied the same volume as 0.184 g of hydrogen at 17 °C at the same pressure. What is the molar mass of the gas ?

Q 3.

What is the unit of coefficient of viscosity?

Q 4.

Pressure versus volume graphs for a real gas and an ideal gas are shown in the figure.
ncert-exemplar-problems-class-11-chemistry-chapter-5-states-of-matter-12

Answer the following questions on the basis of this graph.
(i) Interpret the behaviour of real gas with respect to ideal gas at low pressure.
(ii) Interpret the behaviour of real gas with respect to ideal gas at high pressure.
(iii) Mark the pressure and volume by drawing a line at the point where real gas behaves as an ideal gas.

Q 5.

The pressure of a mixture of H2 and N2 in a container is 1200 torr. The partial pressure of nitrogen in the mixture is 300 torr. What is the ratio of  H2  and N2 molecules in the mixture?

Q 6.

Give an expression for the van der Wools equation. Give the significance of the constants used in the equation. What are their units?

Q 7.

Which of the following figures does not represent 1 mole of dioxygen gas at STP?
(a) 16 grams of gas                                                                
(b) 22.7 litres of gas
(c) 6.022 x 1023 dioxygen molecules
(d) 11.2 litres of gas

Q 8.

Name two intermolecular forces that exist between HF molecules in liquid state.

Q 9.

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.

Q 10.

What will be the pressure of the gas mixture when 0.5 L of H2 at 0.8 bar and 2.0 L of dioxygen at 0.7 bar are introduced in all vessel at 27 °C?

Q 11.

Explain the physical significance of vander Waals parameters.

Q 12.

Name four properties of gases.

Q 13.

Arrange the following in order of increasing density:
ncert-solutions-for-class-11th-chemistry-chapter-5-states-of-matter-33

Q 14.

Name two phenomena that can be explained on the basis of surface tension.

Q 15.

What do you understand by laminar flow of a liquid?

Q 16.

Write van der Waals equation for n moles of a gas.

Q 17.

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

Q 18.

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)

Q 19.

What is SI unit of (i) Viscosity (ii) Surface tension?

Q 20.

What is the effect of temperature on (i) surface tension and (ii) Viscosity?

Q 21.

What are real gases ?

Q 22.

Give mathematical expression for ideal gas equation.

Q 23.

Why liquids diffuse slowly as compared to gases?

Q 24.

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?

Q 25.

A gas that follows Boyle's law, Charles' law and Avogadro's law is called an ideal gas. Under what conditions a real gas would behave ideally?

Q 26.

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.

Q 27.

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.

Q 28.

Compressibility factor, Z, of a gas is given as Z = PV/nRT
(i) What is the value of Z for an ideal gas?
(ii) For real gas what will be the effect on value of Z above Boyle's temperature?

Q 29.

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.

Q 30.

Density of a gas is found to be 5.46 g/dm3 at 27 °C and at 2 bar pressure. What will be its density at STP?

Q 31.

What is meant by elastic collision ?

Q 32.

(a) What do you mean by’Surface Tension'of a liquid?
(b) Explain the factors which can affect the surface tension of a liquid.

Q 33.

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.

Q 34.

Why does sharp glass edge become smooth on heating it up to its melting point in a flame? Explain which property of liquids is responsible for this phenomenon.

Q 35.

Explain the term ‘laminar flow'. Is the velocity of molecules same in all the layers in laminar flow? Explain your answer.

Q 36.

What will be the pressure exerted by a mixture of 3.2g of methane and 4.4g of carbon dioxide contained in a 9 dm3 flask at 27 °C?

Q 37.

What is the value of the gas constant in SI units?

Q 38.

Define boiling point of a liquid.

Q 39.

What is Boyle Temperature?

Q 40.

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.

Q 41.

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.

Q 42.

The variation of vapour pressure of different liquids with temperature is shown in figure
ncert-exemplar-problems-class-11-chemistry-chapter-5-states-of-matter-20

(i) Calculate graphically boiling points of liquids A and B.
(ii) If we take liquid C in a closed vessel and heat it continuously, at what temperature will it boil?
(iii) At high altitude, atmospheric pressure is low (say 60 mm Hg). At what temperature liquid D boils?
(iv) Pressure cooker is used for cooking food at hill station. Explain in terms of vapour pressure why is it so?

Q 43.

Isotherms of carbon dioxide gas are shown in figure. Mark a path for changing . gas into liquid such that only one phase (i.e. either a gas or liquid) exists at any time during the change. Explain how the temperature, volume and pressure should be changed to carry out the change.

ncert-exemplar-problems-class-11-chemistry-chapter-5-states-of-matter-22

Q 44.

What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30 °C?

Q 45.

Calculate the total number of electrons present in 1.4 g of dinitrogen gas.

Q 46.

How much time would it take to distribute one Avogadro number of wheat grains if 1010 grains are distributed each second ?

Q 47.

What do you mean by compressibility factor?

Q 48.

Define critical temperature of gas.

Q 49.

State Dalton's law of partial pressure.

Q 50.

How is compressibility factor expressed in terms of molar volume of the real gas and that of the ideal gas?