In This Post we are providing Chapter-5 States of Matter NCERT MCQ for Class 11 Chemistry which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.
NCERT MCQ ON STATES OF MATTER
Question 1.
The vapor 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
Explanation:
Vapor pressure depends on T only and it does not depend on container volume.
Question 2.
Name the liquid with higher vapor pressure in the following pairs:
(a) Alcohol, glycerin (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
Explanation:
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.
Question 3.
The rate of diffusion methane is twice that of X. The molecular mass of X is
(a) 64.0
(b) 32.0
(c) 40
(d) 80
Answer: (a) 64.0
Explanation:
Let rate of diffusion of gas x, r1 = a
Therefore, rate of diffusion of methane, r2 = 2 a
According to Grahams Law of Diffusion
(r1r2) = (M2M1−−−√)
M1 = Molecular mass of gas x
M2 = Molecular mass of Methane = 16 g
Therefore, (a2a) = (16M2−−−√)
Squaring both the sides, (14) = (16M2)
or, M2 = 16 × 4 = 64 g
Question 4.
The state of matter that shows the uniformity of behavior :
(a) Solid Liquid
(b) Liquid
(c) Gas
(d) None of the Above
Answer: (c) Gas
Explanation:
Of the three states of matter, the gaseous state is the simplest and shows greatest uniformity in behaviour. Gases show almost similar behaviour irrespective of their chemical nature. This state is characterized by:
Gases maintain neither the volume nor the shape. They completely fill the container in which they are placed.
They expand appreciably on heating. Gases are highly compressible. The volume of the gas decreases when the pressure increases. They diffuse rapidly into space. Gases exert equal pressure in all directions.
All gases are colourless except a few e.g. chlorine (greenish yellow) bromine (reddish brown), nitrogen dioxide (reddish brown)
The behaviour of gases can be described by certain quantitative relationships called gas laws. They give the relationship between mass, pressure, volume and temperature.
Question 5.
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 bonds
Answer: (a) Attract one another
Explanation:
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.
Question 6.
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 Pressure
Answer: (d) Units of Volume, Temperature and Pressure
Explanation:
The value of the gas constant R depends on the units used for pressure, volume and temperature.
Question 7.
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
(a) A
(b) B
(c) C
(d) D
Answer: (d) D
Explanation:
Vc = 3b = 3 × 4N × (4/3) πr³
Question 8.
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
Explanation:
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.
Question 9.
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
Explanation:
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.
Question 10.
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
Answer: (a) 30 L
Explanation:
According to the ideal gas equation, we have
PV = nRT
PV = (wM) RT
V = (wM) (RTP)
Given values are:
w = 2.8 g
M = Molar mass of CO = 28 g mol-1
T = 27°C = (273 + 27) = 300 K
P = 0.821 atm
R = 0.0821 L atm mol-1 K-1
Putting the values in the formula we get :
V = (2.8 g /28 g mol-1) × (0.0821 L atm mol-1 K-1) × (300 K)/(0.821 atm)
= 3 L
Question 11.
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
Explanation:
At constant T, P1V1 = P2V2
1 × 20 = P2 × 50;
P2 = (2050) × 1
Question 12.
How many of the know elements exist as gases at 25°C?
(a) 9
(b) 11
(c) 12
(d) 15
Answer: (b) 11
Question 13.
The states of matter having no definite shape but definite volume:
(a) Gas
(b) Liquid
(c) Solid
(d) None of the Above
Answer: (b) Liquid
Explanation:
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.
Question 14.
The rise or fall of a liquid within a tube of small bore is called:
(a) Surface Tension
(b) Capillary Action
(c) Viscosity
(d) Formation of Curvature
Answer: (b) Capillary Action
Explanation:
Capillarity, rise or depression of a liquid in a small passage such as a tube of small cross-sectional area, like the spaces between the fibres of a towel or the openings in a porous material. Capillarity is not limited to the vertical direction. Water is drawn into the fibres of a towel, no matter how the towel is oriented.
Liquids that rise in small-bore tubes inserted into the liquid are said to wet the tube, whereas liquids that are depressed within thin tubes below the surface of the surrounding liquid do not wet the tube. Water is a liquid that wets glass capillary tubes; mercury is one that does not. When wetting does not occur, capillarity does not occur.
Capillarity is the result of surface, or interfacial, forces. The rise of water in a thin tube inserted in water is caused by forces of attraction between the molecules of water and the glass walls and among the molecules of water themselves. These attractive forces just balance the force of gravity of the column of water that has risen to a characteristic height. The narrower the bore of the capillary tube, the higher the water rises. Mercury, conversely, is depressed to a greater degree, the narrower the bore.
Question 15.
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) Rutherford’s Atomic Theory
(d) Kinetic Molecular Theory
Answer: (d) Kinetic Molecular Theory
Explanation:
The kinetic molecular theory (KMT) is a simple microscopic model that effectively explains the gas laws described in previous modules of this chapter. This theory is based on the following five postulates described here. (Note: The term “molecule” will be used to refer to the individual chemical species that compose the gas, although some gases are composed of atomic species, for example, the noble gases.)
Gases are composed of molecules that are in continuous motion, travelling in straight lines and changing direction only when they collide with other molecules or with the walls of a container.
The molecules composing the gas are negligibly small compared to the distances between them.
The pressure exerted by a gas in a container results from collisions between the gas molecules and the container walls.
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