Updated Chemistry MCQs – New States Of Matter ( Chemistry ) MCQs
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Chemistry MCQs – States Of Matter ( Chemistry ) MCQs
The most occurred mcqs of States Of Matter ( ) in past papers. Past papers of States Of Matter ( Chemistry ) Mcqs. Past papers of States Of Matter ( Chemistry ) Mcqs . Mcqs are the necessary part of any competitive / job related exams. The Mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related States Of Matter ( Chemistry ) Mcqs. The Important series of States Of Matter ( Chemistry ) Mcqs are given below:
Kinetic Energy and Molecular Speeds
1. Calculate the root mean square speed of hydrogen in m/s at 27°C?
a) 2835.43 m/s
b) 2635.43 m/s
c) 2735.43 m/s
d) 2731.43 m/s
Answer: c
Explanation: The formula of root mean square speed is given by urms = \sqrt{3RT/M}. We have R = 8.314 kgm2/s2, M = 10-3 kg/mol and T = 300 k. So by substituting the formula we get, urms = \sqrt{3×8.314×300/10^{-3}} = 2735.43 m/s.
2. What is the ratio of urms to ump in oxygen gas at 298k?
a) 1.124
b) 1.224
c) 1.228
d) 1.128
Answer: b
Explanation: The ratio of root mean square speed, represented as urms to the most probable speed, represented as ump is always the same for identical conditions and same gas. It is 3RT/M−−−−−−−√ divided by 8RT/πM−−−−−−−−√ = 1.224.
3. The speed of three particles is recorded as 3 m/s, 4 m/s, and 5 m/s. What is a root mean square speed of these particles?
a) 4.082 m/s
b) 2.07 m/s
c) 3.87 m/s
d) 3.082 m/s
Answer: a
Explanation: The root means square speed of particles is nothing but the square root over the sum of squares of the particle’s speeds by a total number of particles. So by substituting, √32 + 42 + 52/3 = 4.082 m/s.
4. What is the ratio of root mean square speed of 16 grams of Oxygen to 4 grams of hydrogen?
a) 2
b) 3
c) 4
d) 1
Answer: a
Explanation: The formula of root mean square speed of particles is given as 3RT/M−−−−−−−√. We know that the velocity of gas molecules is inversely proportional to the root over the mass of the gas here the mass of oxygen to the mass of hydrogen ratio is the answer. So 16/4−−−−√ = 2.
5. Which of the following is greater for identical conditions and the same gas?
a) most probable speed
b) average speed
c) root mean square speed
d) most probable and average speed have the same value
Answer: c
Explanation: According to the formula, the root mean square speed is greater than the average speed and the average speed is greater than the most probable speed at given identical conditions and for the same gas.
6. The root mean square speed of a gas at a certain condition is 1.128 times greater than the most probable speed.
a) true
b) false
Answer: b
Explanation: The ratio of root mean square speed to the mean probable speed is 1.224. So the above statement is considered to be wrong. The ratio between the main probable speed and the average speed and root mean square speed is 1: 1.128: 1.224.
7. What is the most probable speed of oxygen gas with the mass of 32 grams at 27-degree centigrade?
a) 33.74 m/s
b) 44.78 m/s
c) 57.94 m/s
d) 549.14 m/s
Answer: b
Explanation: The formula for the most probable speed of a gas is given as 8RT/πM−−−−−−−−√. Here R is a universal gas constant which is always equal to 8.314 kgm2s-2, T=300 Kelvin and M = 0.032 kg So by substituting, we get an answer as 44.78 m/s.
8. Which among the following options do you think has the highest average speed?
a) chlorine
b) hydrogen
c) neon
d) oxygen
Answer: b
Explanation: The formula of average speed is given by 2RT/M−−−−−−−√, where R is universal gas constant, T is a temperature in Kelvin and M is the mass in kilograms. From the formula, we understand that the average speed is inversely proportional to the root over the mass. As hydrogen has the least mass among the options it has the highest average speed.
9. What is the ratio of the velocities of 2 moles of hydrogen to five moles of helium?
a) 14−−√
b) 10−−√
c) 20−−√
d) 50−−√
Answer: b
Explanation: The formula of average speed is given by 2RT/M−−−−−−−√. We know that the velocity of gas molecules is inversely proportional to the root over the mass of the gas. So here the ratio of velocities is 5×4/2×1−−−−−−−−−√ = 10−−√.
10. What is the mean velocity of one Mole neon gas at a temperature of 400 Kelvin?
a) 11.533 m/s
b) 357.578 m/s
c) 367.79 m/s
d) 34 m/s
Answer: a
Explanation: The formula for mean velocity of a gas is given by the expression 2RT/M−−−−−−−√. for one mole of neon gas M is taken as 0.02 kg, temperature as 400 k, R as 8.314 kgm2s-2, so by substituting we get an answer as 11.533 m/s.
Kinetic Molecular Theory of Gases
1. Which of the following assumption explains great compressibility of gases?
a) the actual volume of the gas molecules is negligible
b) there is no force of attraction
c) particles are always in random motion
d) different particles have different speeds
Answer: a
Explanation: Gas molecules are considered as point masses because the actual volume of gas molecules is negligible when compared to the space between them, so this assumption explains the greater compressibility of gases.
2. Gases ________ and occupy all the space that is available to them.
a) contract
b) compress
c) expand
d) shrink
Answer: c
Explanation: At normal temperature and pressure, there is no force of attraction between the gas particles. So they expand and occupy the space that is available. This statement supports the assumption.
3. Gases do not have a fixed shape.
a) true
b) false
Answer: a
Explanation: Particles do not have a fixed shape because they are always in random motion and particles never occupy fixed position the keep on moving and never occupy a particular shape this is the reason to prove that the above statement is true.
4. Why do you think the pressure is exerted by the gas on the walls of the container in all directions?
a) they consist of identical particles
b) collide with each other during random motion
c) lack of definite shape
d) more forces of attraction
Answer: b
Explanation: As the particles of gas travel in straight lines and move in a random motion and collide with each other and also collide with the walls of the container, the pressure is exerted on the walls of the container in all directions.
5. Collisions of gas molecules are ___________
a) perfectly elastic
b) inelastic
c) always occur in a proper and predicted motion
d) not conserved
Answer: a
Explanation: The total energy of molecules before the collision is equal to the total energy after the collision. That means there may be an exchange of energy between the molecules but the total energy does not change, so the collisions of gas molecules are elastic.
6. At an instance different particles have ________ speeds.
a) same
b) different
c) opposite
d) similar
Answer: b
Explanation: According to the kinetic molecular theory of gases, the assumption that different particles have different speeds at a time is because particles do not always have the same speeds and move in different directions but we can assume that the distribution of speeds is constant at a particular temperature.
7. There is an increase in temperature of an object then the kinetic energy of the object __________
a) decreases
b) increases
c) remains the same
d) it is not related to the temperature
Answer: b
Explanation: From the kinetic molecular theory of gases we can know that the kinetic energy of an object is proportional directly to the Absolute Temperature of that object so when the temperature of an object increases obviously the kinetic energy also increases.
8. The temperature of a gas is 100 K it is heated until it is 200 k then, what do you understand regarding kinetic energy in this process?
a) halved
b) tripled
c) quadrupled
d) doubled
Answer: d
Explanation: According to the kinetic molecular theory of gases, if the Absolute Temperature of a gas is doubled then the kinetic energy is also doubled because they are directly proportional to each other so here the answer is doubled. If the temperature doubles from 100 k to 200 k, kinetic energy also doubles.
9. Which of the following is not a postulate of Kinetic molecular theory of gases?
a) the actual volume of gas molecules is negligible
b) there are high forces of attraction between the gas molecules
c) collisions are elastic in gas molecules
d) kinetic energy of gas molecules is directly proportional to the absolute temperature
Answer: b
Explanation: According to Kinetic molecular theory of gases, there are no forces of attraction between the particles of gas at normal temperature and pressure. This is because gases expand and occupy all the space available.
10. Which of the following statements do you think is the correct one?
a) in gases there is a predominance of intermolecular energy
b) all molecules have the same speed at different temperatures
c) collisions of gas molecules are elastic
d) do not exert the same pressure in all directions
Answer: c
Explanation: Collisions are elastic as the total amount of energy before and after the collision is the same. The correct statements of the incorrect ones are: in gases, there is a predominance of thermal energy, the distribution of speeds remains constant at a particular temperature and the gases exert the same pressure in all directions of the container.
Behaviour of Real Gases: Deviation from Ideal Gas Behaviour
1. The plot PV vs v at constant temperature is a straight line for real gases.
a) true
b) false
Answer: b
Explanation: The plot of PV vs P is not a straight line for real gases because they deviate from Ideal behaviour. are there are two types of deviations one is a positive deviation and the other is a negative deviation.
2. PV/nRT is known as ____________
a) compressibility factor
b) volume factor
c) pressure factor
d) temperature factor
Answer: a
Explanation: PV/nRT is known as compressibility factor and is represented by the letter Z. It is a ratio of PV and nRT; where p is pressure, V is volume, n is the number of moles, R is the universal gas constant and T is temperature.
3. Which of the following conditions do you think a real gas behaves as an ideal gas?
a) high pressure
b) low pressure
c) intermediate pressure
d) at any pressure
Answer: b
Explanation: At low-pressure conditions, Z = 1 handset behaves as an ideal gas but at high-pressure Z is greater than 1 and for intermediate pressure that is less than 1. So at low-pressure condition, a real gas behaves as an ideal gas.
4. What is the temperature known as where a real gas obeys Boyle’s law or as an ideal gas?
a) Boyle temperature
b) Charge temperature
c) Critical temperature
d) Absolute Temperature
Answer: a
Explanation: The temperature at which a real gas obeys Boyle’s law and other ideal gas law at a certain range of pressure is called Boyle temperature or Boyle point. It is unique for every gas and depends upon its nature.
5. Compressibility can be expressed as _______
a) real volume divided by the ideal volume
b) real universal gas constant by ideal universal gas constant
c) real temperature by ideal temperature
d) real volume divided by real pressure
Answer: a
Explanation: The deviation of real gas behaviour from ideal gas behaviour is known from the compressibility factor. This compressibility factor can also be measured as the ratio of real volume to ideal volume.
6. Above Boyle temperature real gases show __________ deviation from ideal gases.
a) positive
b) negative
c) no
d) both positive and negative
Answer: a
Explanation: Above Boyle temperature, the value of the compressibility factor is greater than 1. So the gases show positive deviation from ideal gases as the forces of attraction between the gas molecules are very low.
7. Which of the following is a corrected equation of ideal gas equation?
a) (P – an2V2)(V – nb) = nRT
b) (P – an2/V2)(V + nb) = nRT
c) (P + an2/V2)(V – nb) = nRT
d) (P – an2/V2)(V – nb) = nRT
Answer: d
Explanation: (P – an2/V2)(V – nb) = nRT; where p is pressure, a is the magnitude of intermolecular attractive forces within a gas, n is the number of moles, v is volume, b is a van der Waal constant, R is the universal gas constant and T is temperature.
8. The value of a in van der Waal equation is _____________ /dependent on ___________
a) pressure
b) temperature
c) pressure and temperature
d) independent of pressure and temperature
Answer: d
Explanation: Value of an in van der Waal equation represents a measure of the magnitude of intermolecular attractive forces within the gas and it is also independent of temperature and pressure. The van der Waal’s equation is given by (P – an2/V2)(V – nb) = nRT.
9. What are the units of “b” in van der Waals equation?
a) L/mol
b) L mol
c) 1/L mol
d) L
Answer: a
Explanation: The ideal gas equation is given as (P – an2/V2)(V – nb) = nRT. So by considering the equation, we can understand that the units of the volume are equal to the units of a number of moles X be so the units of b. So b’s units = volume / number of moles so it is L/mol.
10. A gas that is of 2 moles occupies a volume of about 500 ml at 300 Kelvin and 50 atmospheric pressure, calculate the compressibility factor of the gas.
a) 1.863
b) 0.7357
c) 0.5081
d) 1.8754
Answer: c
Explanation: Compressibility factor Z = PV/nRT; Z = 50 atm x (500/1000) ml / 2 x 0.082 x 300 k = 25/6×8.2 = 0.5081. That means Z < 1, so this is a negative deviation from ideal gas behaviour. So the gas is more compressible than expected.
Liquefaction of Gases
1. Which of The following is a critical temperature for Carbon dioxide?
a) 32-degree centigrade
b) 30.98-degree centigrade
c) 40-degree centigrade
d) 30.91 degree Kelvin
Answer: b
Explanation: The critical temperature of carbon dioxide is a maximum temperature where the carbon dioxide can remain as a liquid below this temperature. The carbon dioxide is gas so the critical temperature for Carbon dioxide is 30.98 degrees centigrade.
2. Which of the following is Greater?
a) Boyle’s temperature
b) Boyle’s temperature = critical temperature
c) Critical temperature
d) Boyle’s temperature = 1/critical temperature
Answer: a
Explanation: Boyle’s temperature TB is given by a/Rb critical temperature TC is given by 8a/27Rb, where a is the pressure correction term and b is a volume correction term as per van der Waal’s equation. So Boyle’s temperature is greater than the critical temperature.
3. What is the ratio of critical temperature to Boyle’s temperature of the same gas?
a) 8/27
b) 27/8
c) 8
d) 27
Answer: a
Explanation: The maximum temperature gas can remain liquid is known as critical temperature. The temperature till which a gas behaves like an ideal gas is Boyle’s temperature. Boyle’s temperature TB is given by a/Rb critical temperature Tc is given by 8a/27Rb. So the ratio is 8/27.
4. A fluid is a _______________
a) gas
b) liquid
c) solid
d) both gas and liquid
Answer: d
Explanation: A fluid is a gas or liquid that can be used to recognize the continuity. The fluid is something deforms under shear stress application and flows from one place to another, it is also a subset of States of matter.
5. A gas that is liquefied by applying pressure below critical temperature is called ____________ of the substance.
a) vapor
b) liquid
c) solid
d) plasma
Answer: a
Explanation: At critical temperature liquid state changes into gaseous state continuously the surface that separates both this state disappears and gas below critical temperature can be liquefied by applying pressure and this is called vapor of the substance.
6. If the value of a is greater, what does it mean?
a) the gas liquefies easily
b) the gas cannot liquify easily
c) gas obeys ideal gas law
d) gas particles have random motion
Answer: a
Explanation: The value of an in van der Waals equation is a measure of the magnitude of intermolecular attractive forces within a gas. It is independent of temperature and pressure. As attractive forces are more, the gas can be liquefied easily.
7. Which of the following can be the value of “b” for Helium?
a) 23.71 x 10-6 m2/mol
b) 23.71 x 10-6 m3/mol
c) 23.71 x 10-6 m3 mol
d) 23.71 x 10-6 m/mol
Answer: b
Explanation: From van der Waal’s equation (P – an2/V2)(V – nb) = nRT, we have that units of volume and number of moles x b are same. So L = mol x b; units of b is L/mol otherwise can be written as m3/mol.
8. The value of b for carbon dioxide is given as 42.69 x 10-6m3/mol. What do you think is the volume of a molecule?
a) 7.59 m3
b) 7.03 m3
c) 76.09 m3
d) 7.09 m3
Answer: d
Explanation: From van der Waal’s equation (P – an2/V2)(V – nb) = nRT, we know that V = b/NA = 42.69 x 10-6m3/mol/6.023 x 1023 molecules/mol. That equals 7.09 m3/molecule. So the volume of a molecule is 7.09m3.
9. In van der Waal’s equation, b is known as ______________
a) volume constant
b) pressure constant
c) volume correction
d) pressure correction
Answer: c
Explanation: In the van der Waal’s equation (P – an2/V2)(V – nb) = nRT, b is the volume correction term and is 4 times as the volume of a molecule. The letter a is the pressure correction term in the van der Waal’s equation.
10. Which of the following is an expression for Boyle’s temperature?
a) a/Rb
b) 27a/R
c) a/b
d) Ra/8b
Answer: a
Explanation: Boyle’s temperature Tb is given a/Rb, where a and b are the van der Waal’s constants for pressure and volume correction. The temperature till which a gas behaves like an ideal gas is Boyle’s temperature.
Liquid State
1. What is the boiling point at pressure 1 atm known as?
a) Standard boiling point
b) Normal boiling point
c) Van der Waal boiling point
d) Saturated boiling point
Answer: c
Explanation: The boiling point at pressure 1 atm is known as normal boiling point. Normal boiling point is slightly greater than the standard boiling point as molecules change into the vapor phase and density of vapor increases.
2. 1 poise = ____________
a) 0.1 kgm-1s-1
b) 1 kgm-1s-1
c) 10 kgm-1s-1
d) 100 kgm-1s-1
Answer: a
Explanation: Poise is the unit of viscosity. It’s S.I. unit is 1 Newton second per square meter. It’s Pascal second. In C.G.S. system, the unit of viscosity is poise that is named after a scientist Jean Louise
Poiseuille. So, it’s 1 poise = 0.1 kgm-1s-1.
3. Viscosity of liquid _________ with rise in temperature.
a) Increases
b) Decreases
c) Remains constant
d) Is independent
Answer: a
Explanation: As there is a rise in temperature the viscosity of liquid increases while the viscosity of gas decreases. In liquids, due to rise in temperature, molecules have high thermal energy so the can overcome intermolecular attractions.
4. In a liquid, the force required to maintain the flow of layers is 5N, velocity gradient in du/dx, area of contact is 20m2. Then what is the value of viscosity?
a) 6.25 dz/du
b) 0.15 dz/du
c) 0.2 dz/du
d) 0.25 dz/du
Answer: d
Explanation: The formula of force required to maintain the flow of layers is given by the formula F = ηAdu/dz, where η is the coefficient of viscosity, A is the area of contact and du/dz is the velocity gradient. So by substituting we get an answer as 0.25dz/du.
5. Path in liquid in which layers do not meet each other is _______
a) laminar flow
b) tubular flow
c) viscosity
d) straight path
Answer: a
Explanation: The type of flow in liquids when each path flows in a different path, that do not interfere with each other is laminar flow. At any point in the fluid, the velocity of a fluid is constant is a characteristic of laminar flow.
6. What is S.I. unit of Surface Tension?
a) Dyne/meter
b) Newton-meter
c) Newton/meter
d) Dyne-meter
Answer: c
Explanation: Surface Tension is the tendency of a fluid to occupy least surface area as possible. It is defined as the force per unit distance. So, the units of surface tension are Newton/meter in S.I. the system, Dyne/cm in C.G.S system.
7. If the angle of contact between the liquid and container is 90 degrees then? (C is the cohesive and A is the Adhesive force)
a) C > A
b) C = A
c) C < A
d) C is not equal to A
Answer: b
Explanation: When the angle of contact between the liquid and container is 90 degrees then the cohesive and adhesive forces in a liquid are equal. Cohesive force is the attraction between similar atoms and adhesive between different atoms.
8. A water drop is spherical in shape due to ____________
a) Viscosity
b) Poise
c) Surface tension
d) Reflection
Answer: c
Explanation: Surface Tension is the tendency of a fluid to occupy least surface area as possible. It is defined as the force per unit distance. So, the spherical shape that is acquired by a water drop is due to surface tension.
9. The surface tension of ___________ at critical temperature.
a) one
b) zero
c) two
d) three
Answer: b
Explanation: The surface tension in liquids decreases with rise in temperature. As surface tension decreases, molecules become more active when temperature increases and surface tension becomes zero at critical temperature TC.
10. Higher the viscosity, the slower the liquid flows.
a) True
b) False
Answer: a
Explanation: Viscosity is defined as the resistance to the flow of a liquid. It opposes a liquid’s layer movement with respect to one another. So, the above statement: the higher the viscosity, the slower the liquid flows is true.