Q.1. The rate of diffusion of methane is twice that of X. The molecular mass of X is
Q.2. Which of the following is not a type of van der Waal’s forces?
(a) Dipole – dipole forces
(b) Dipole – induced dipole forces
(c) Ion – dipole forces
(d) London forces
Answer(c) Attractive forces between an ion and a dipole are known as ion – dipole forces and these are not van der Waals forces.
Q.3. The vapour pressure of water at 300 K in a closed container is 0.4 atm. If the volume of container is doubled, its vapour pressure at 300 K will be
(a) 0.8 atm
(b) 0.2 atm
(c) 0.4 atm
(d) 0.6 atm
Answer(c) 0.4 atm
Vapour pressure depends on T only and it does not depend on container volume.
Q.4. Who proposed the concept of dispersion force ?
(a) Heitler and London (b) van der Waal
(c) Gay Lussac (d) Fritz London
Answer(d) Fritz London explained the concept of dispersion force.
Q.5. The interaction energy of London force is inversely proportional to sixth power of the distance between two interacting particles but their magnitude depends upon
(a) charge of interacting particles
(b) mass of interacting particles
(c) polarisability of interacting particles
(d) strength of permanent dipoles in the particles.
Q.6. Name the liquid with higher vapour pressure in the following pairs:
(a) Alcohol, glycerine (b) Petrol, kerosene (c) mercury, water.
(a) Alcohol, Water, Petrol
(b) Petrol, Water, Alcohol
(c) Alcohol, Petrol, Water
(d) None of these
Answer(c) Alcohol, Petrol, Water
The vapour pressure of the liquid is inversely proportional to the magnitude of the intermolecular forces of attraction present. Based on this, the liquid with higher vapour pressure in the different pairs is: (a) Alcohol, (b) Petrol, (c) Water.
Q.7. Dipole-dipole interaction is stronger than the London forces but is weaker than ion-ion interaction because
(a) only partial charges are involved
(b) only total charges are involved
(c) both (a) and (b)
(d) sometimes (a) and sometimes (b)
Answer(a) Dipole-dipole interaction is stronger than the London forces but is weaker than ion-ion interaction because only partial charges are involved e.g., HCl molecules. The attractive force decreases with the increase of distance between the dipoles.
Q.8. Dipole-induced dipole interactions are present in which of the following pairs :
(a) Cl2 and CCl4 (b) HCl and He atoms
(c) SiF4 and He atoms (d) H2O and alcohol
Q.9. The state of matter that shows the uniformity of behavior :
(a) Solid Liquid
(d) None of the Above
Q.10. When you heat a sample of gas, what happens to the particles that make up the gas?
(a) The particles move faster.
(b) The particles break apart
(c) The particles get smaller
(d) The particles become more denseAnswer
Q.11. Strength of the hydrogen bond is determined by interaction between the
I. lone pair of the electronegative atom and the hydrogen atom of other atom.
II. bond pair of the electronegative atom and the hydrogen atom of other atom.
Identify the correct option.
(a) Only I is correct
(b) Only II is correct
(c) Both I and II are correct
(d) Neither I nor II are correct
Answer(a) Strength of the hydrogen bond is determined by coulombic interaction between lone pair electrons of the electronegative atom of one molecule and the hydrogen atom of the other molecule.
Q.12. Which of the following statement is wrong for gases?
(a) Gases do not have definite shape and volume
(b) Volume of the gas is equal to the volume of the container confining the gas
(c) Confined gas exert uniform pressure on the wall of the container in all directions
(d) Mass of the gas cannot be determined by weighing a container in which it is contained
Answer(d) Mass of the gas cannot be determined by weighing a container in which it is contained
Mass of the gas = mass of the cylinder including gas – mass of empty cylinder. So mass of a gas can be determined by weighing the container in which it is enclosed. Thus, the statement (d) is wrong for gases.
Q.13. A gas deviates from ideal behavior at a high pressure because its molecules:
(a) Attract one another
(b) Show the Tyndall Effect
(c) Have kinetic energy
(d) Are bound by covalent bondsAnswer
Answer(a) Attract one another
The basic concept of the kinetic-molecular theory give us the information why real gases deviate from ideal behavior. The molecules of an ideal gas are assumed to occupy no space and have no attractions for one another. Real molecules, however, do have finite volumes, and they do attract one another. So, a gas deviates from ideal behavior at a high pressure because its molecules attract one another.
Q.14. Which of the following is the correct order of thermal energy in three states of matter ?
(a) Solid < Liquid < Gas (b) Liquid < Gas < Solid
(c) Liquid < Solid < Gas (d) Gas < Solid < Liquid
Q.15. The value of universal gas constant R depends on
(a) Temperature of Gas
(b) Volume of Gas
(c) Number of Moles of Gas
(d) Units of Volume,Temperature and PressureAnswer
Answer(d) Units of Volume, Temperature and Pressure
The value of the gas constant R depends on the units used for pressure, volume and temperature.
Q.16. Which one of the following statements is not correct about the three states of matter i.e., solid, liquid and gaseous ?
(a) Molecules of a solid possess least energy whereas those of a gas possess highest energy.
(b) The density of solid is highest whereas that of gases is lowest
(c) Gases like liquids possess definite volumes
(d) Molecules of a solid possess vibratory motion
Answer(c) Gases do not have definite shape and volume. Their volume is equal to the volume of the container.
Q.17. The critical volumes of four gases A, B, C, D are respectively 0.025 L, 0.312 L, 0.245 L, 0.432 L, the gas with highest value of van der Wall constant b is
Q.18. Which of the following is true about gaseous state ?
(a) Thermal energy = Molecular attraction
(b) Thermal energy >> Molecular attraction
(c) Thermal energy << Molecular attraction (d) Molecular force >> Those in liquids
Answer(b) It is characteristic of gases i.e., Thermal energy >> molecular attraction.
Q.19. At constant temperature, for a given mass of an ideal gas
(a) the ratio of pressure and volume always remains constant.
(b) volume always remains constant.
(c) pressure always remains constant.
(d) the product of pressure and volume always remains constant.
Q.20. In van der Waal equation of state of gas laws, the constant b is a measure of
(a) Intermolecular collisions per unit volume
(b) Intermolecular attraction
(c) Volume occupied by the molecules
(d) Intermolecular repulsions
Answer(c) Volume occupied by the molecules
In van der Waals equation of state of the gas law, the constant b is a measure of the volume occupied by the molecules. It gives the effective size of the gas molecules. The greater value of b indicates a larger size of the molecules and smaller compressible volume.
Q.21. Boyle’s law states that the
(a) pressure of a gas is directly proportional to the temperature at constant volume
(b) pressure of a gas is inversely proportional the volume at constant temperature
(c) volume is directly proportional to the temperature at constant pressure
(d) None of the above
Q.22. The volume of 2.8 g of carbon monoxide at 27°C and 0.0821 atm is
(a) 30 L
(b) 3 L
(c) 0.3 L
(d) 1.5 L
Q.23. Air at sea level is dense. This is a practical application of
(a) Boyle’s law (b) Charle’s law
(c) Kelvin’s law (d) Brown’s law
Q.24. If 20cm³ gas at 1 atm. is expanded to 50 cm³ at constant T, then what is the final pressure
(a) 20 × 150
(b) 50 × 120
(c) 1 × 120 × 50
(d) None of these
Answer(a) 20 × 150
At constant T, P1V1 = P2V2
1 × 20 = P2 × 50;
P2 = (2050) × 1
Q.25. The law, which states that at constant temperature, the volume of a given mass of gas is inversely proportional is pressure, is known as:
(a) Boyles law
(b) Charles law
(c) Combine gas law
(d) Avogadros lawAnswer
Q.26. Use of hot air balloons in sports and meteorological observations is an application of
(a) Boyle’s law (b) Charle’s law
(c) Kelvin’s law (d) Gay-Lussac’s law
Q.27. How many of the know elements exist as gases at 25°C?
Q.28. An ideal gas is one which obeys the gas laws under
(a) a few selected experimental conditions
(b) all experimental conditions
(c) low pressure alone
(d) high temperature alone
Answer(b) An ideal gas obeys the gas laws under all experimental conditions.
Q.29. The states of matter having no definite shape but definite volume:
(d) None of the Above
In a liquid, particles will flow or glide over one another, but stay toward the bottom of the container. The attractive forces between particles are strong enough to hold a specific volume but not strong enough to keep the molecules sliding over each other.
Q.30. Pure hydrogen sulphide is stored in a tank of 100 litre capacity at 20° C and 2 atm pressure. The mass of the gas
(a) 34 g (b) 340 g
(c) 282.68 g (d) 28.24 g
Q.31. The rise or fall of a liquid within a tube of small bore is called:
(a) Surface Tension
(b) Capillary Action
(d) Formation of Curvature
Answer(b) Capillary Action
Q.32. Gas equation PV = nRT is obeyed by
(a) Only isothermal process
(b) Only adiabatic process
(c) Both (a) and (b)
(d) None of these
Answer(c) PV = nRT is for an ideal gas which follows both isothermal and adiabatic processes.
Q.33. The theory which explains that gases consist of molecules, which are in rapid option is known as:
(a) Daltons Atomic Theory
(b) Bohrs Theory
(c) Rutherfords Atomic Theory
(d) Kinetic Molecular TheoryAnswer
Answer(d) Kinetic Molecular Theory
Q.34. The total pressure of a mixture of two gases is :
(a) the sum of the partial pressures
(b) the difference between the partial pressures
(c) the product of the partial pressures
(d) the ratio of the partial pressures
Answer(a) By Dalton’s law of partial pressures, the total pressure of a mixture of two gases is the sum of the partial pressures of components of the mixture.
Q.35. Falling drop of water is spherical due to:
(a) Hydrogen Bonding
(b) Surface Tension
(c) Capillary Action
Answer(b) Surface Tension
Raindrops take up the spherical shape due to the surface tension of water which is caused due to the tendency of water molecules to stick together. The spherical shape is having the least possible surface area due to which it can resist any of the external force in the atmosphere.
Q.36. The rates of diffusion of gases are inversely proportional to square root of their densities . This statement refers to:
(a) Daltons Law
(b) Grahams Law
(c) Avogadros Law
(d) None of the Above
Answer(b) Grahams Law
Q.37. If helium and methane are allowed to diffuse out of the container under the similar conditions of temperature and pressure, then the ratio of rate of diffusion of helium to methane is:
(a) 2 : 1
(b) 1 : 2
(c) 3 : 5
(d) 4 : 1
Q.38. 56 g of nitrogen and 96 g of oxygen are mixed isothermally and at a total pressure of 10 atm. The partial pressures of oxygen and nitrogen (in atm) are respectively
(a) 4, 6 (b) 5, 5
(c) 2, 8 (d) 6, 4
Q.39. What is the ratio of pressure of the 2gm of hydrogen to that of 4 gm of helium at temperature of 298K, 20ml
volume? (consider the ideal behaviour)
(a) 1 : 2 (b) 2 : 1
(c) 1 : 1 (d) 2 : 2
Answer(c) Number of moles, temperature and volume are same.
Q.40. Which among the following has lowest surface tension ?
(a) Hexane (b) Water
(c) CH3OH (d) CH3CH2OH